An Egyptian journalist couple and a lawyer are facing charges of joining a "terrorist group," their lawyer confirmed on Thursday, after they were detained amid a string of similar arrests.

Security forces detained husband and wife Hossam El-Sayed and Solafa Magdy, as well as lawyer Mohamed Salah, from a Cairo cafe on Tuesday.

Nabeeh Elganadi, a member of the journalists' defense team, said on Thursday that all three were held in relation to a case involving "recently arrested professors, lawyers, and journalists."

He said state security prosecutors had charged freelance journalist Magdy, her photojournalist husband El-Sayed and lawyer Salah with joining a "terrorist group."

Magdy was also charged with disseminating false news.

Elganadi filed a complaint with the attorney-general's office on Thursday over Magdy's claims of torture at the hands of police at the Dokki station, where she was taken after being arrested.

"Police struck her arms and side as well as verbally hurling abuse at her. They also impounded her car and took her mobile phone," he said.

All three will remain in detention for 15 days, which can be renewed indefinitely.

Egyptian police on Sunday detained then released three editors at local news outlet Mada Masr, after arresting another editor the day before.

Human rights agencies on Wednesday accused Egypt of building a "parallel justice system" to crack down on critics and dissent. They described the state security prosecution as a "tool of repression."

Since President Abdel Fatah al-Sisi led the military ouster of former Islamist president Mohamed Morsi in 2013, a crackdown has ensnared activists, journalists and dissidents.

New York-based watchdog Committee to Protect Journalists roundly criticized the authorities' renewed targeting of the journalists and dissidents.

"Egyptian authorities have clearly learned nothing after the international outcry over their recent detentions of journalists, and are determined to continue a losing strategy," it said in a statement.