Egyptian authorities on Thursday shut down a rights group that treats torture victims, the latest in a series of such government attempts against El Nadeem Center for the Rehabilitation of Victims of Violence and Torture.

"A great police force has sealed the centre with red wax on our off-day," Aida Seif Elldawla, a psychiatrist and one of the centre's co-founders told Ahram Online.

No staff member was there at the time, Seif Elldawla said, adding that police forces arrested the doorman, questioned him and let him go.

"This is the latest in a series of attacks against whoever says an opposing word in this country."

Authorities have attempted on numerous occasions over the past year to shut down El Nadeem Centre, which provides psychological support to victims of torture and to families of missing individuals.

In February 2016, the government ordered the closure of the centre without providing an official reason. The centre challenged the order in court and has continued to operate.

Two months later, authorities tried to shut down the centre again without showing official documentation but its doctors refused the order.

In November, the group's bank account was suspended pending its registration as a non-governmental organisation before it was lifted a week later.

Nadeem is already registered as a clinic with the health ministry.

Also in November, Seif Elldawla was banned from traveling to Tunisia to attend a conference on the rehabilitation of torture victims in North Africa.

Late last year, Egypt's parliament approved a contentious bill that regulates the activities of NGOs in Egypt, a move that sparked fears of tightening restrictions on civil society.

The law was sent to President Abdel-Fattah El-Sisi to sign into law.