The releases were announced as dozens of jailed Kurds continued a four-day-old hunger strike to protest against the "torture and inhumane treatment" they have suffered behind bars, said prominent lawyer and rights activist Anwar Bunni.
"Fifty-five political prisoners were transferred from Saydnaya prison to a branch of military security where they were released," said the Syrian Human Rights Association on Saturday.
The association "welcomes this measure, and calls for the step to be completed by releasing all prisoners of conscience and to stop illegal arrests," the group said, publishing the names of 46 of those released.
Last December, 112 Syrian political prisoners, most of them members of the banned Muslim Brotherhood, were released after a presidential pardon.
Hunger strike continues
Meanwhile, more than 50 Kurds, including 10 women, from the Kurdistan Workers Party (PKK), pushed on with a hunger strike started on Tuesday to protest against the torture they say they have suffered in jail, Bunni said.
The group was arrested in May 2004 during an anti-PKK crackdown in Syria. Damascus backed the PKK - renamed the Kongra-Gel - in its armed struggle against the Turkish authorities in the southeast of the country until 1998.
Syria then expelled Kurdish rebel leader Abd Allah Ocalan and signed a security deal with Ankara, pledging to stop supporting the PKK.
Rights groups estimate there are about 2000 political prisoners in Syria, including 200 Kurds.