Manama , Bahrain ( CNN ) -- Bahrain 's king ordered the release of a number of prisoners and closed cases against several Shia leaders accused of plotting against the kingdom , the country 's state news agency said early Tuesday . King Hamad ibn Isa Al Khalifa named the leaders during a national unity speech last year , leading to the arrest of several of them and the exile of several others who were out of the country at the time . The announcement clears the way for the return of Hassan Mushaimaa , leader of Bahrain 's largest opposition party , the Haq Movement . Mushaimaa said he planned to arrive in Manama Tuesday evening -- amid early speculation that he would be arrested . `` I know that thousands will be waiting for me , '' said Mushaimaa , who said he planned to give a speech in Bahrain on Tuesday about the importance of national unity . Thousands more people moved into Pearl Roundabout on Monday , a presence that has taken on an air of permanence since government forces retreated on Saturday and demonstrators reoccupied the symbolic location . Tents , some of them outfitted with furniture and occupied by entire families , dot the square . The mass protests planned for Tuesday in support of calls for political reforms and other concessions and coincided with Mushaimaa 's return.. `` If the people want a new system in a constitutional kingdom , I will be with them , '' he said . `` If the people just want to change the regime , I will also be standing beside them . '' Mushaimaa , who has been living abroad , had previously been detained by the government for campaigning for more democratic rights in the island monarchy . In September , Bahrain said it requested Interpol -- the world 's largest international police organization -- to help in arresting Mushaimaa , who the government accused of a terrorist plot to destroy state buildings and of planning a coup . But the king 's decision closed the books on the case against Mushaimaa , giving him the freedom to return without fear of arrest . Meanwhile , fallout from last week 's violent protests continues . A 20-year-old protester in Bahrain , who was shot in the head on Friday , has died , hospital sources said Monday . Ridha Mohammed was advancing toward the Pearl Roundabout with other demonstrators when security forces opened fire . Prior to Mohammed 's death , about 10 protesters were thought to have died in five days of protests , but opposition activists say dozens more are unaccounted for . Bahrain canceled its participation in a Grand Prix auto race that had been scheduled to begin March 11 . Testing for the race had been scheduled to start March 3 , and protest organizers had threatened to disrupt the event . The race apparently will be rescheduled , but no date has been selected , race officials said . In announcing the decision , Crown Prince Salman said , `` We felt it was important for the country to focus on immediate issues of national interest and leave the hosting of Bahrain 's Formula 1 race to a later date . '' The country hopes to host the race `` in the very near future , according to Zayed R. Alzayani , chairman of the Bahrain International Circuit . State television on Monday broadcast images of pro-government demonstrators who gathered near a mosque in the capital city , holding flags and chanting slogans including `` Long live the king . '' Also on Monday , Standard & Poor 's downgraded Bahrain 's credit rating by one step and advised investors that it believes continued protests could result in a further degradation of the country 's ability to meet its financial obligations . `` We expect the demonstrations that have taken place over the past month will persist , '' the agency wrote . Protesters initially took to the streets of Manama last week to demand reform and the introduction of a constitutional monarchy . But some are now calling for the removal of the royal family , which has led the Persian Gulf state since the 18th century . Young members of the country 's Shiite Muslim majority have staged violent protests in recent years to complain about discrimination , unemployment and corruption , issues they say the country 's Sunni rulers have done little to address . The Bahrain Center for Human Rights says authorities launched a clampdown on dissent in late 2010 . It accused the government of torturing some human rights activists .
NEW : The decision means a self-exiled opposition leader wo n't be arrested when he returns Tuesday . `` I know that thousands will be waiting for me , '' says Mushaimaa . In the past few days there have been several reports of violence in Bahrain and Saudi Arabia against anti-government protesters. Bahrain postpones Formula 1 race because of protests .