The director of a prominent Egyptian rights group was held in solitary confinement and inhumane conditions for three days after his arrest last week, his lawyers and the group's founder said on Monday.
Gasser Abdel Razek is one of three staff from the Egyptian Initiative for Personal Rights (EIPR) arrested last week in a case that has drawn public criticism from the United Nations and Western diplomats.
The interior ministry, which is responsible for prisons, could not be immediately reached for comment.
The arrests, on charges including joining a terrorist group and publishing false news, came after senior diplomats visited EIPR for a briefing on human rights on November 3.
"Gasser is being deliberately singled out even compared to other prisoners in the Liman Tora prison for inhumane and degrading treatment that is meant to cause him harm and that is putting his health and safety at risk," Hossam Bahgat, the founder and chairman of EIPR, told Reuters after Abdel Razek appeared at an investigation session at a Cairo court.
Abdel Razek's head had been shaved, he had no warm clothing and he'd been given a metal bed with no mattress, Bahgat said.
An urgent request had been made to review the conditions which were "in violation of the constitution and the law", said Negad El Borai, a defence lawyer.
The arrests of the EIPR staff have been criticised by a number of European states, the United States, and Canada. Prominent US Democrats and President-elect Joe Biden's pick for his secretary of state, Antony Blinken, have also expressed concern.
Egypt's foreign ministry said on Saturday it rejected "any attempt to influence the investigations being conducted by the Public Prosecution" and that work in any domain must be performed as regulated by the law.
Critics see the arrests as the latest escalation of an unprecedented crackdown on civil society and political dissent overseen by Egyptian President Abdel Fattah al-Sisi.
Sisi has said there are no political prisoners in Egypt and that stability and security are paramount.
Separately, Egypt on Monday designated as terrorists 28 people including Alaa Abdel Fattah, a prominent liberal activist most recently arrested in September 2019, according to the official gazette.