The move comes after Syrian President Bashar al-Assad won the general presidential election by a landslide, said director of the UK-based Syrian Observatory for Human Rights Rami Abdel Rahman.
The inmates include 400 men and 80 women and 20 of them have been already released, Rahman added.
On Thursday, Syrian government also released 320 prisoners from the Aleppo Central Prison.
A couple of weeks ago, Syrian army special forces broke a long siege on the Aleppo Central Prison imposed by al-Qaeda-linked insurgent groups.
RA/MB