Prominent Egyptian dissident Alaa Abdel Fattah was detained Sunday morning beyond his overnight probation, his family and a judicial official said.

His lawyer was also later detained while attending an interrogation of the activist, according to the Egyptian Center for Economic and Social Rights.

State security prosecutors had “finished questioning” Abdel Fattah and were “now interrogating the human rights lawyer Mohamed al-Baqer, who was arrested while attending the interrogation” of his client, the rights group said.

Earlier on Sunday, Abdel Fattah’s sister Monah Seif, also an activist, had tweeted: “We don’t know where Alaa is… The police station says he’s most probably at state security prosecution.”

Abdel Fattah, 37, is serving five years of probation after completing a five-year jail sentence in March for staging a protest against a 2013 law effectively banning public gatherings.

His probation requires him to report to a police station near his home in Cairo at 6:00 PM every evening, and stay overnight in a cell until 6:00 AM.

On Sunday morning, however, he was not released.

Officers denied his mother Laila Soueif access to the police station and refused to say why he had not been released, his sister said.

The activist and computer programmer’s whereabouts remain unknown and no word has been given on when he might appear before prosecutors, the judicial official told AFP.

Abdel Fattah told AFP in June that security personnel had ordered him twice to stop talking about his probation publicly or face being sent back to jail indefinitely.

A prolific tweeter, he has commented on small-scale protests held in Egypt in the last week or so.

The demonstrations followed an online call to dissent by an exiled Egyptian businessman.

Some 2,000 people have been arrested in the past week in what may be the largest expansion of an ongoing crackdown in Egypt since 2013, rights groups say.

Authorities have detained other prominent critics including well-known academics, politicians and lawyers.

Abdel Fattah has advocated on behalf of other detainees, calling for a more humane and flexible system of probation.