A Syrian court has released two activists after nearly two months in detention for having taken part in anti-regime demonstrations, their lawyer said on Monday.

"The judges on Sunday released Bahraa Abdel Nabil Hijazi and Anas Abdel Salam after 53 days of detention," Michel Shammas told AFP.

Hijazi, whose father is a prominent author and journalist, is a director of short films and documentaries, while Abdel Salam is pro-democracy campaigner.

They were accused of "forming a secret organisation" and "taking part in anti-regime protests" when they were arrested.

Shammas said their trial would be held at a later date.

He called for the release of all Syrian prisoners, including his daughter Yara who was arrested on March 7, along with 11 other youths, at a cafe in Damascus.

"My daughter is not a Salafi or a jihadist and does not belong to any radical group," he said, adding the regime was refusing to acknowledge the extent of a year-old popular uprising and was likening it to terrorism.

Amnesty International says thousands of opponents of the Syrian government have been arrested since pro-democracy protests erupted in March 2011, and that many were believed to have been tortured or otherwise ill-treated.

At least 9,100 people have been killed since the revolt began, according to monitors.