U.N. office: Early reports suggest most casualties were caused by authorities Send us you photos and videos, but please stay safe. (CNN) -- The political turmoil dividing Egypt threatens the future of the nation, the defense minister said, as the instability persists in the Arab world's most populous country. CNN iReport: Inhaling tear gas, breaking the curfew It's the latest in the seesaw struggle between Egypt's first democratically elected president and dissidents who say his tenure is a throwback to past dictatorships, particularly the reign of President Hosni Mubarak, who was toppled in a popular revolt two years ago. Egypt's defense minister has denied reports that the army used live ammunition on protesters, state-run media reported. Interior Minister Mohamed Ibrahim told police forces Sunday that he understands the challenges and demands they've faced, saying "together with your brothers at the armed forces, you constitute the country's shield and fort in face of all dangers." "You've faced unprecedented and systematic patterns of violence," he said. Your security during these confrontations is my goal. Ibrahim huddled with Prime Minister Hisham Qandil on Monday over state of emergency arrangements, including maintaining peaceful expression, but also dealing firmly with saboteurs targeting police. The Transport Ministry said that despite the tumult in the Suez Canal region, the unrest has not affected shipping operations to or from the eastern and western ports of Port Said or the traffic at the El Arish port. What's behind the latest wave of violence in Egypt? Black Bloc labeled terrorist group Egyptian Prosecutor General Talaat Abdullah has listed one anti-government group, the Black Bloc, as a terrorist entity. Authorities say its members are often seen wearing black ski masks, waving their trademark black flag while taking part in some of the most violent attacks against police and security forces. The designation raises the specter of the government taking a more aggressive stance against anti-government protesters. The group says its mission is to fight government corruption and oppression. The government has often used the Black Bloc's aggressive tactics to depict anti-government protesters as part of an insurgency that wants to topple Egypt's leadership. Morsy calls for talks But a key opposition leader issued conditions before accepting Morsy's call for talks. The group made several demands before it would urge people to stop protesting, including the formation of a new government and making changes to what it called the "distorted constitution" that voters passed in a referendum last month. U.N. human rights official weighs in In addition, as many as 25 female protesters reportedly have been sexually assaulted in Cairo's Tahrir Square over the past few days, "in some cases with extraordinary violence," the statement said. She said the state of emergency should be governed by the rule of law, in line with international standards. She urged Morsy to listen to the demands of demonstrators and take action to deal with problems in the judicial system. She said that all "stakeholders" should be involved in reviewing legislation on demonstrations, associations and access to public information. "I urge the Government to take urgent measures to ensure that law enforcement personnel never again use disproportionate or excessive force against protestors, firstly because it is illegal to do so, and secondly because it is likely to make the situation even more explosive," Pillay said. At the same time, it is unacceptable and a dereliction of duty not to intervene when protestors are being attacked by thugs and when women are being raped and sexually assaulted. CNN's Amir Ahmed, Salma Abdelaziz and Joe Sterling contributed to this report.