Egypt's official human rights body on Monday blamed security forces and "armed elements" among protesters for the death of hundreds during the dispersal of a massive Islamist sit-in last August.
The National Council for Human Rights said 632 people, including 8 policemen, were killed on August 14 when security forces dispersed Cairo's Rabaa al-Adaweya sit-in, organised by supporters of deposed Islamist president Mohamed Morsi.
The day-long clashes as police and soldiers moved in to break up the sprawling tent city, more than a month after Morsi's overthrow by the military, led to the worst mass killing in modern Egyptian history.
The council was commissioned by the government to investigate human rights violations during the dispersal but also in the following months.
"Most of the civilian victims are (protesters) who could not escape the armed clashes" between security forces and gunmen, the council said in a report distributed to journalists during a press conference.
It did not say who killed them, but accused police of using disproportionate force.
"We are not condemning anyone ... we are demanding a judicial investigation to know who killed whom," Nasser Amin, a member of the council, told reporters.
Security forces were "obliged to use firearms" but "failed in maintaining proportionality regarding the intensity of the fire", the report said.
Since the army ousted Morsi in July, the military-installed authorities have been waging a deadly crackdown on his supporters, killing more than 1,400 people according to Amnesty International.
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Thousands, including Morsi and most of the Brotherhood's leaders, have been detained.
The report said the armed clashes that erupted in the sit-in began after "some armed elements suddenly opened fire" and killed an officer calling on protesters to disperse.
It added that the 25-minute notice given by security forces to protesters to leave the sit-in was "not enough to allow the exit of thousands of (protesters) in the first hours of the day."
Security forces "failed in securing" a safe path to allow protesters to leave safely, it said.
But the report also said armed individuals "used the protesters as human shields, putting them in the fire of security forces during the clashes."
The council aired footage of a sniper shooting from the roof of a military building and a protester falling on the ground after being shot. It also showed video of black-clad riot police beating a protester in custody.
But other footage shown at the press conference showed armed protesters firing on security forces and the testimony of a man who said he was tortured by protesters days before the dispersal.
Amin said the council had sent an official request to the interior ministry, in charge of the police, asking for the plan to disperse the sit-in, without getting a response.
Neither Morsi's Muslim Brotherhood nor the security forces cooperated with the council, he added.
"The parties involved in the struggle are trying to hide their abuses."