A U.N. team said on Tuesday it had counted 52 bodies in a makeshift morgue at an Iranian dissident camp, most with gunshot wounds and some with their hands tied, two days after violence that it decried as an "atrocious crime".
The dissident Mujahadin-e-Khalq (MEK) group blamed the Iraqi army for Sunday's bloodshed, but an adviser to Prime Minister Nuri al-Maliki, whose government is close to Iran, dismissed the accusation as baseless.
Following a visit to Camp Ashraf on Monday, the U.N. team said most of the corpses had gunshot wounds to the head and upper body. It said several buildings in the camp were also damaged, including one which was burnt out.
"I call on the Iraqi government to ensure that a thorough, impartial and transparent investigation into this atrocious crime is conducted without delay and that the results of the investigation are made public," Gyorgy Busztin, acting U.N. envoy to Iraq, said in a statement.
A spokesman for the Iraqi government could not be immediately reached for comment. But the adviser to Maliki, Ali al-Moussawi, said on Sunday the prime minister had ordered an investigation into what had happened.
Before the violence there were about 100 MEK Iranian exiles at Camp Ashraf, which the Iraqi government wants closed down.
The bloodshed, also condemned by Britain and the United States, took place hours after a mortar bomb attack. Two security sources said on Sunday that the army and special forces had opened fire on residents who stormed a post at the entrance to the camp, allegations denied by Maliki's adviser.
The sources had said at least 19 people were killed. A U.N. statement at the time had a death toll of 47, while MEK said 52 were killed.
Last year, most of the camp's inhabitants were relocated to a former U.S. military base in north eastern Baghdad known as Camp Liberty, which has come under attack twice this year. The U.N. is currently processing them for refugee status abroad.
Camp Ashraf's remaining residents said on Tuesday that seven people were still unaccounted for after the violence and that they believed they had been taken as hostages by Iraqi forces.
A woman who identified herself as the daughter of one of those missing said MEK members at Camp Liberty had gone on hunger strike to demand the return of the seven and were holding the United Nations responsible for ensuring their safety.
MEK, which the U.S. State Department removed from its list of terrorist organizations last year, wants Iran's clerical leaders overthrown and fought on former Iraqi dictator Saddam Hussein's side during the Iran-Iraq war in 1980s.
The group is no longer welcome in Iraq under the Shi'ite Muslim-dominated government that came to power after U.S.-led forces toppled Sunni strongman Saddam in 2003.