'The Syrian authorities should now release all prisoners of conscience and long term political prisoners who have been languishing in jail for years, cut off from the ouside world and their loved ones while serving sentences passed after grossly unfair trials,' the organisation added.

Those released - apparently as a result of an amnesty issued by President Bashar al-Assad - included 'Imad Zinko, Mahmud 'Uthman, Hashim Majzub, and Khaled al-Shami. All of them are leading members of the Muslim Brotherhood who had been in detention since the early 1980s following violent confrontations between the Muslim Brotherhood and the Syrian authorities.

All were held for most of their detention period at Tadmur Military Prison from where they were moved to Sednaya Prison in recent months. They were mostly held incommunicado during the course of their detention and subjected to torture and ill-treatment while held in cruel, inhuman and degrading conditions.