Human Rights Watch (HRW) on Tuesday called for the release of an Egyptian doctor, arrested in January, who had been investigating prison health care for the country's medical union.
Taher Mokhtar, as well as two roommates arrested along with him when police raided their central Cairo apartment, is accused of planning violent protests to overthrow the government and intimidate and terrorize citizens, the New York-based rights group said.
"The allegations appear to stem from Mokhtar's political activism – including organizing doctors' strikes and protesting for police accountability – and his work documenting medical neglect in Egypt's detention facilities," according to the HRW statement.
The group's call for his release comes amid rising tensions between authorities and the country's professional unions after security forces raided the Egyptian Journalists' Syndicate headquarters in central Cairo on Sunday night in order to arrest two journalists.
Security forces blocked off the street around the syndicate building on Tuesday ahead of a planned press conference and protest, allowing entry only to syndicate members.
Police prevented officials of the medical and engineering unions from visiting to express their support, the vice president of the Egyptian Medical Syndicate, Mona Mina, said.
Members of the syndicate draped a black banner from the building with the words "Journalism is not a crime," news site al-Bedaiah reported.
The Journalists Syndicate has demanded the sacking of Interior Minister Magdi Abdul-Ghaffar and has called a general assembly of its members for Wednesday.
The Interior Ministry denied that its forces had "stormed" the syndicate building and said that the journalists had given themselves up peacefully when police informed them of their arrest warrants.
State newspaper al-Ahram, in an unusual show of dissent, on Tuesday described the raid as "shameful behaviour" in an unsigned editorial and said that the sacking of Abdul-Ghaffar was "an expected step."
The "mistakes" of the Interior Ministry "will not succeed in their vile aim of shutting mouths and stifling the freedom of opinion and expression," according to the editorial.
Egyptian authorities have clamped down on civil liberties since President Abdel-Fattah al-Sissi, then head of the armed forces, ousted Islamist president Mohammed Morsi in 2013.