Supporters of President Morsi detained 83 opposition "thugs" during clashes at the presidential palace on Wednesday, Abdel-Moneim Abdel-Maqsoud, a lawyer for the Muslim Brotherhood, has said.
The suspects were not handed over to the police immediately, Abdel-Maqsoud told Turkey's Anadolu news agency. They were held until the prosecution and forensic experts had inspected the available evidence.
The detained persons had confessed to killing six members of the Brotherhood and injuring hundreds of others, he added.
"The 83 'thugs' were arrested with money, white weapons and Molotov cocktails," Abdel-Maqsoud claimed. "They admitted causing riots and killing and injuring hundreds of [the president's] supporters."
The Brotherhood has filed reports with the general prosecutor against those it accuses of involvement in the violence at the presidential palace, and of burning Brotherhood and Freedom and Justice Party offices in various part of the country.
"We have clear-cut and documented evidence that proves major politicians and media figures incited the violence," he said.
The presidential guard ordered protesters to leave the area around the presidential palace by 3pm on Thursday, presidential spokesperson Yasser Ali said earlier in the day.
Pro-Morsi supporters on Wednesday attacked a peaceful sit-in by opposition activists calling for the constitutional referendum on 15 December to be cancelled. Six people have been reported killed and over 600 injured in the resulting violence.