Image caption A government helicopter dropped leaflets on protesters in Rabaa al-Adawiya square in Cairo urging them to go home 
 
 US senators John McCain and Lindsey Graham are due to arrive in Cairo as diplomatic efforts to end Egypt's political crisis intensify. 
 
 US and EU envoys have been meeting officials from the military-backed government and supporters of ousted President Mohammed Morsi. 
 
 Their talks took place amid mounting tension over plans to break up two mass sit-ins by Morsi loyalists in Cairo. 
 
 A government helicopter dropped leaflets urging people to leave. 
 
 The pamphlets, which were dropped over the Rabaa al-Adawiya square, pledged protesters would face no action if they had not committed a crime whilst demonstrating. 
 
 More than 100 Morsi supporters have been killed in clashes since the president was overthrown by the military on 3 July. 
 
 Meanwhile a court in Cairo said it would start the trial of Muslim Brotherhood leader Mohammed Badie and two of his deputies on 25 August. 
 
 Mr Badie and several other senior Brotherhood figures were arrested on charges of inciting violence and complicity in the deaths of anti-Morsi demonstrators during rallies in July. 
 
 A Brotherhood spokesman rejected the charges last month as "nothing more than an attempt by the police state to dismantle" the protests. 
 
 Prevent bloodshed 
 
 Mr McCain and Mr Graham are expected to land in the Egyptian capital on Monday evening for two days of negotiations. 
 
 Over the weekend, US deputy secretary of state, William Burns, already held separate talks with members of Mr Morsi's Muslim Brotherhood and the Egyptian Foreign Minister, Nabil Fahmy. 
 
 The European Union's envoy, Bernardino Leon, also joined the meeting with Mr Fahmy. 
 
 Few official details have been given, but the hope is clearly to prevent further violence and bloodshed, correspondents say. 
 
 The foreign ministers of Qatar and the United Arab Emirates are also involved in the diplomatic push, and are reported to have visited a Muslim Brotherhood leader. 
 
 Meanwhile further talks took place between army chief Gen Abdul Fattah al-Sisi and a prominent group of Islamic clerics. 
 
 According to an army statement, Gen al-Sisi told the clerics a peaceful solution could be reached if all sides rejected violence. 
 
 However, the preachers were heavily criticised by Morsi loyalists for taking part in the meeting; they say nothing short of Mr Morsi's reinstatement will end their protests. 
 
 On Saturday, the interior ministry renewed its call for the demonstrations to end peacefully, and said this would allow the Muslim Brotherhood to return to a role in the democratic political process. 
 
 Thousands of Morsi supporters have been defying warnings from the authorities to abandon the sit-ins in Cairo at Nahda Square and outside the Rabaa al-Adawiya mosque, in the east of the capital. 
 
 The protesters and their families have been camping there for weeks, demanding the ousted president's reinstatement. ||||| CAIRO — Three top officials of Egypt’s Muslim Brotherhood will go on trial on Aug. 25, on charges of inciting members of their group to kill rioters in front of its headquarters during the upheaval that led to President Mohamed Morsi’s ouster on July 3, a Cairo court ruled on Sunday. 
 
 Although the authorities have detained dozens of Brotherhood members since Mr. Morsi’s fall from power, the case against the group’s spiritual leader, his deputy and another key figure is the first to be scheduled for trial. 
 
 The pending prosecutions are a new blow to the Brotherhood, which emerged as the country’s strongest political movement after the ouster of President Hosni Mubarak in 2011, but has seen all of its newfound power stripped away in a matter of weeks. 
 
 The scheduling of the trial will most likely further complicate intensive political and diplomatic efforts to persuade Mr. Morsi’s supporters to break up two large sit-ins in Cairo that they have committed to maintaining until he is restored to power. 
 
 Egypt’s new military-backed government has said it would not let the sit-ins continue indefinitely, but many fear that efforts to forcefully disperse the protesters would unleash new violence. Envoys from the European Union, Qatar, the United Arab Emirates and the United States have tried to help broker a solution. 
 
 The prosecutions could be an effort to put more pressure on the group to strike a deal to end the current crisis, said Shadi Hamid of the Brookings Doha Center. 
 
 The case concerns events during the final days of Mr. Morsi’s tenure, when hundreds of rioters — equipped with stones, Molotov cocktails and firearms — attacked the Muslim Brotherhood’s headquarters in Cairo and tried to burn those inside alive. 
 
 Police officers in the area during the attack did not intervene, and a few men inside the darkened building fired guns from the windows. Health officials said eight people were killed outside the building, and a video posted online showed one badly beaten man being dragged from the building. 
 
 Accused of incitement to murder in the case are the Brotherhood’s supreme guide, Mohamed Badie; his deputy, Khairat el-Shater; and another official, Mohamed Bayoumi. 
 
 Three other defendants in the case have been charged with murder and arms possession, and an additional 29 people have been accused of using force, terrifying residents and attacking a police officer, state news media reported. 
 
 Mr. Hamid said the prosecution represented an escalation of the military’s campaign against the Brotherhood. 
 
 “It reflects a real desire on the part of some in the organization to use this opportunity to destroy the Brotherhood,” he said. 
 
 Even under Mr. Mubarak, whose security services routinely detained and tortured Brotherhood members and other Islamists, the supreme guide was mostly left alone. 
 
 A serving supreme guide of the Brotherhood has not been arrested since 1981, before Mr. Mubarak came to power. 
 
 In a separate case, the prosecutor general ordered the detention of Mr. Morsi’s former chief of staff and his deputy for 15 days for investigation into charges that they incited the detention and torture of protesters by Brotherhood members in 2012. 
 
 Mr. Morsi, who has been detained in an undisclosed location since his ouster, is also under investigation for purported collaboration with the Islamist militant group Hamas and his escape from prison during the uprising that led to Mr. Mubarak’s ouster. 
 
 Also Sunday, authorities at Cairo airport denied entry to Tawakkul Karman, the Yemeni activist and Nobel Peace Prize winner, who had flown to Egypt to join a pro-Morsi sit-in, state news media reported. They did not give a reason for refusing entry to Ms. Karman, a member of Yemen’s largest Islamist party, who won the prize in 2011 for her role in the uprising that led to the fall of that country’s president, Ali Abdullah Saleh, and who has recently spoken out against Mr. Morsi’s removal from power. ||||| MINYA, Egypt An Egyptian court sentenced the leader of the outlawed Muslim Brotherhood and 682 supporters to death on Monday, intensifying a crackdown on the movement that could trigger protests and political violence ahead of an election next month. 
 
 The Brotherhood, in a statement issued in London, described the ruling as chilling and said it would "continue to use all peaceful means to end military rule". 
 
 An Islamist alliance that includes the Brotherhood called on Egyptians to demonstrate against the death sentences in the streets of Cairo on Wednesday. 
 
 In another case signaling growing intolerance of dissent by military-backed authorities, a pro-democracy movement that helped ignite the uprising that toppled autocrat Hosni Mubarak in 2011 was banned by court order, judicial sources said. 
 
 The death sentence for Mohamed Badie, the Brotherhood's general guide, will infuriate members of the group, which has been the target of raids, arrests and bans since the army forced President Mohamed Mursi from power in July. 
 
 The United States and the United Nations expressed alarm over the ruling. 
 
 Some Brotherhood members fear pressure from security forces and the courts could drive some young members to violence against the movement's old enemy, the Egyptian state. 
 
 Islamist militants based in the Sinai Peninsula have stepped up attacks against security forces since Mursi's overthrow, killing hundreds. 
 
 On Monday night, Cairo authorities found two bombs that were planted in the car of an army officer, security officials said. 
 
 Badie, considered a conservative hardliner, was charged with crimes including inciting violence that followed the army overthrow of Mursi, who is also on trial on an array of charges. 
 
 The slight, 70-year-old veterinary professor stood trial in Cairo in a separate case hours after the sentence was affirmed. 
 
 "If they executed me one thousand times I will not retreat from the right path," Badie was quoted as saying by lawyer Osama Mursi, who attended one of his trials in Cairo. 
 
 The comments were published on the Facebook page of Osama Mursi, son of the Brotherhood leader ousted as president. 
 
 Two security officials told Reuters that Badie appeared relaxed and joked, asking other Brotherhood members to buy him the red outfit that prisoners condemned to death wear. 
 
 Tough measures against the Brotherhood suggest the authorities still see it as a major threat, even though most of its leaders and thousands of members are behind bars. 
 
 Authorities are well aware that the movement founded in 1928 has survived repression under successive Egyptian autocrats. 
 
 BROTHERHOOD SUPPORT 
 
 The White House said it was "deeply troubled" by the ruling. 
 
 "Today's verdict, like the one last month, defies even the most basic standards of international justice," it said in a statement. Secretary of State John Kerry would raise U.S. concerns in a meeting with the Egyptian foreign minister on Tuesday, Kerry's spokeswoman said. 
 
 The Obama administration said last week that it would partly resume military aid to Egypt, six months after cutting off the assistance in the wake of Mursi's ouster. The administration is delivering 10 Apache helicopters to Cairo and has notified Congress of its intention to send $650 million in aid for weapons systems used for border security, counterterrorism, anti-smuggling and non-proliferation. 
 
 Some U.S. lawmakers said they were closely reviewing the decision to send Egypt the money, saying they wanted to know for certain who would use the money - and how. 
 
 "I want to find out, are they going to have a legitimate election? I'm not going to invest in a country that's in a state of anarchy," U.S. Senator Lindsey Graham, the top Republican on the Senate subcommittee that oversees foreign aid, told Reuters. 
 
 The Brotherhood, believed to have about 1 million supporters in the nation of 85 million, has vowed to topple the government through protests. 
 
 Reacting to what it called the "chilling" court ruling, the Brotherhood said the world can no longer afford to stay silent. 
 
 "The Muslim Brotherhood reaffirms it will continue to fight relentlessly for freedom and democracy in Egypt, and continue to use all peaceful means to end military rule and achieve justice for the Egyptian people," the group's London office said in an emailed statement. 
 
 In a separate case, a court affirmed death sentences on 37 others. The rulings were part of a final judgment on 529 Muslim Brotherhood supporters condemned last month. The remaining defendants were jailed for life, judicial sources said. 
 
 Death sentence recommendations in the case involving Badie will be passed on to Egypt's Mufti, the highest religious authority. His opinion can be ignored by the court. The rulings can be appealed. Many defendants are on the run. 
 
 Mass trials in the biggest Arab state have reinforced fears among human rights groups that the government and anti-Islamist judges are using all levers of power to crush opponents. 
 
 "The decisions are possibly the largest possible death sentences in recent world history. While they're exceptional in scale, they're certainly not exceptional in kind," said Sarah Leah Whitson, executive director for Middle East and North Africa at Human Rights Watch. 
 
 "It seems that these sentences are aimed at striking fear and terror into the hearts of those who oppose the interim government." 
 
 The political turmoil that has gripped Egypt and a fast-growing Islamist insurgency have harmed the economy, which grew by a meager 2.1 percent last year. 
 
 "In a month, Egypt sentences more people to death than the rest of the world combined. It is not the kind of news to rekindle confidence," Angus Blair, chairman of business and economic forecasting think-tank Signet, wrote on Twitter. 
 
 PRO-DEMOCRACY MOVEMENT BANNED 
 
 As word spread of the death sentences, relatives screamed and cried outside the court in the town of Minya. 
 
 "This is a corrupt government. This is a failed regime. We have no real police. We have no real state," said Sabah Hassan, whose son was sentenced to death. 
 
 Others collapsed on the street as soldiers with AK-47 assault rifles standing on an armored vehicle looked on. 
 
 Relatives blamed Abdel Fattah al-Sisi, the general who deposed Mursi. The former head of military intelligence under Mubarak is expected to easily win presidential elections on May 26-27 in a country long ruled by men from the military, Mursi's time in office representing the rare exception. 
 
 Some people chanted: "Sisi is ruling like a king" and "May God punish you for what you did". 
 
 Authorities have extended a crackdown to secular activists. 
 
 A ruling on Monday banning the activities of the April 6 movement follows the imprisonment of three of its leading members last year on charges of protesting illegally. Charges against April 6 included "damaging the image of the state". 
 
 (Additional reporting by Stephen Kalin and Tom Perry in Cairo, David Brunnstrom, Patricia Zengerle and Jeff Mason in Washington; Writing by Michael Georgy; Editing by Ralph Boulton, Cynthia Osterman and Ken Wills)
– A month after Mohamed Morsi was driven from power in Egypt, three leading Muslim Brotherhood figures face an impending trial. A Cairo court ruling yesterday will send Brotherhood supreme guide Mohammed Badie, deputy Khairat al-Shater, and top official Mohamed Bayoumi to court on Aug. 25 for allegedly inciting the killing of rioters outside the organization's headquarters. Badie's arrest marked the first for a Brotherhood supreme guide since 1981, the New York Times notes. The trial could mark an effort to shut down continuing protests by Brotherhood backers, including a pair of sit-ins, says an expert, adding that some opponents see it as an "opportunity to destroy the Brotherhood." Meanwhile, demonstrations continue, with thousands of Morsi supporters taking to the streets in a Cairo march today, Reuters reports. "We are not terrorists," they chanted as they called for the former leader's reinstatement. Security forces didn't move to halt the protest, but a government helicopter dropped literature at the sit-ins urging protesters to leave. Sens. John McCain and Lindsey Graham are set to arrive in Cairo today, the BBC reports; they join other US and EU officials in a push for resolution.