Security forces dispersed an anti-protest law demonstration in downtown Cairo on Saturday using tear gas.
Footage showed protesters and security forces throwing stones at each other.
The Way of the Revolution Front, an anti-military and anti-Muslim Brotherhood group, called for the protest, dubbed "We are ready to turn ourselves in," Saturday in front of Cairo's Abdeen Court against Egypt's controversial protest law and in solidarity with detained activists.
Participants were asked to demonstrate at 11am in white clothing, the colour worn by detainees, in defiance of the law that demands protests be authorised in advance of being held.
"Put on your white track suit, so they'd know we are ready to turn ourselves in but we will not be broken by a repressive law that bars protesting," said the group on their official Facebook page, adding that they will demand the rights of their comrades who were "tortured and humiliated for only taking part in a protest against military trials for civilians in the constitution."
Two demonstrations on Tuesday — one commemorating a protester killed last year, and the other a rally against military trials for civilians — were dispersed promptly by police, with dozens of demonstrators arrested.
A group of female detainees were released on a desert highway after being allegedly beaten and sexually assaulted by police. Some 24 male protesters remain in custody.
The 24 protesters will be detained for 15 days pending investigations into charges that they violated the new law and assaulted security forces, rights lawyers reported Friday. They started a hunger strike Thursday in protest at their treatment, while their lawyers withdrew from interrogations of the detained men, alleging that the defendants had been subject to torture.
Meanwhile, arrest warrants were issued last week for prominent activist Alaa Abdel-Fattah and Ahmed Maher, founder of the April 6 Youth Movement, accusing them of calling for Tuesday's protests without taking the necessary steps required by the new law on demonstrations.
Alaa was arrested at his home late Thursday after he'd announced he'll turn himself in spite of the fact that he did not call for the protests. Maher has announced he will turn himself in on Saturday. A protest by members of the April 6 Youth Movement was called for in front of the public prosecutor's office in solidarity with Maher.
Six female activists who are part of the No to Military Trials group presented themselves to the prosecution office Wednesday and stated that they were the organisers of the protest.
No charges were brought against them, and they were not detained.
The protest law, issued last Sunday by Interim President Adly Mansour, requires protest organisers to notify authorities three days in advance of a protest's aims and demands, imposing heavy jail terms and fines on individuals who break the law.