A number of people detained during the 5 December clashes between supporters of President Mohamed Morsi and his opponents have accused the Muslim Brotherhood of torturing them.

Clashes broke out around the presidential palace when Morsi supporters descended on an opposition sit-in and dispersed it, removing the tents and assaulting the protesters, including women, say the opposition. The clashes intensified when more opposition protesters joined and the resulting violence led to nine deaths and more than 700 injuries.

The clashes followed a contentious decree issued by Morsi in late November that granted him extraordinary powers. Morsi has called for a referendum on Saturday on a draft constitution rushed through to avert the current crisis.

The opposition National Salvation Front said on Wednesday it would campaign for a 'no' vote rather than a boycott if the referendum goes through with the requisite judicial supervision and appropriate security measures. If these conditions were not met, it would call for a boycott.

Liberals, secularists, Christians and other critics say the draft is full of obscurely worded clauses that could give clerics the power to introduce sharia law. They say the 100-member constituent assembly tasked to draft the constitution was packed with Islamists and ultraconservatives who ignored other groups' concerns.

During the fighting earlier this month, Muslim Brotherhood members captured and detained opposition protesters, holding them for hours and beating them, according to the testimonies of those present. This was done in the plain sight of security forces present at the palace who did not intervene, they claim.

Ola Shahba said she was kept tied up for hours in a republican guard kiosk outside the walls of the palace. "They caught me and were looking for the cross on my wrist, thinking I was Christian. I was beaten and detained. The police supervised the detainment, one officer was joking with them about which one of them would do me over. They insisted that I was paid to be there, and asked me silly questions about which embassy I went to to receive funds," she said.

An ex-diplomat, Yehia Negm, said he had also been detained in the same group. He said he was interrogated over which embassy he received funding from, and he said that Muslim Brotherhood leaders were present.

The Muslim Brotherhood has denied all accusations of firing on protesters. In a statement released the day after the clashes, the government accused protesters of plotting against them. "The plot ended with an attempt to storm the presidential palace in order to topple the regime and oust the legitimate head of state. This was aborted when pro-Morsi demonstrators sacrificed their lives and shed their blood to protect the legitimacy of the revolution and popular will." The statement also offered condolences to the families of "our martyrs".

Reda Senussi, whose brother Mohamed, 22, was shot that night, alleged that members of the Muslim Brotherhood approached his family at the morgue hoping to convince them to have his brother's body included in a funeral procession arranged by the Brotherhood over their fallen. The Brotherhood has said that all the casualties from that night were from their side.

Reda said his brother was returning from work when he was shot and was not affiliated with either side.

The ninth death following the clashes was confirmed by the ministry of health on Wednesday. Journalist Al-Husseini Abu Deif was declared clinically dead after being shot in the clashes. Journalists gathered in front of the journalists' syndicate in Cairo for a memorial.