Ghanem, arrested in March, was sentenced to six months by a military court in Raqqa for "offending President Bashar al-Assad, undermining the image of the state and incitement to sectarian dissent", said the organisation's chief, lawyer and rights activist Ammar al-Qorabi.

The writer had been accused of publishing articles deemed critical of internal Syrian affairs.

Abdo was arrested in 2004 after clashes in the north of the country and sentenced to two and a half years by the state security court in Damascus for "provoking sectarian dissent".

Five days of clashes in March 2004 pitting Kurds against security forces and Arab tribal elements in Qamishli and Aleppo resulted in 40 deaths, according to Kurd sources. The authorities said 25 people were killed.

On Friday another Syrian Kurd, Abdo Khallaf Wallo, was freed by the authorities on the grounds of ill health.

The 65-year-old activist and former leader of the Democratic Union party had been detained because of "his political activity in general and his role in the events of March 2004", Qorabi said.