Activists in Alexandria have claimed they were "terrorised" and threatened with rape after they were arrested during clashes in the city on 21-22 January.
Speaking at a press conference on Tuesday, Mohamed Ezzeddin, a young activist, said police at Borg El-Arab prison threatened to rape him and other detainees.
"We were ordered by police officers to take off our clothes and stay in the cold. We were also threatened with being attacked by Central Security Forces," Ezzeddin added.
Ezzeddin was one of dozens of activists, including minors, arrested in Alexandria during clashes with police on 21-22 January. The clashes began when judges stepped down one day before a verdict was due on police officers accused of killing protesters during Egypt's revolution.
He said he was arrested a few miles away from the clashes, which were taking place outside the Alexandria criminal court. A policeman pointed a gun at his head and he was dragged to a police vehicle along with a friend who "was beaten on the head until he lost consciousness."
Nour El-Zorba, another activist, who was released after being detained for 14 days, said the prison was "run by police officers who terrorise weak prisoners and treat them in an inhumane way."
"Despite what happened to us inside the prison we will not change our ideas and we will not stop struggling against the oppressive regime of Mohamed Morsi," added El-Zorba.
Relatives of the detained were also present at the press conference. The mother of Mohamed Kassab, who is still being detained, said her son was not involved in the clashes and was arrested randomly.
"My son is a respectful young man, a law student not a thug," she said.