Michel Kilo is one of Syria's leading writers

The pair were convicted of spreading false information, encouraging sectarian strife and weakening national sentiment, a Syrian rights group said.

The men were arrested last year after signing a petition that called on Syria to improve its relations with Lebanon.

Several other prominent government critics and rights campaigners have been jailed in Syria in recent weeks.

Michel Kilo is a veteran democracy activist and one of the country's leading writers.

Mahmoud Issa is a translator and former political prisoner who has already spent eight years in jail.

They were arrested a year ago after they signed a petition calling for a radical reform of Lebanese-Syrian relations.

This has been a particularly sensitive subject for Damascus since the assassination of former Lebanese Prime Minister Rafiq Hariri in 2005.

UN investigations have implicated Syrian and Lebanese officials in the killing, although Damascus has denied any involvement.

The petition was signed by 300 Syrian and Lebanese intellectuals.

Other prominent signatories have received heavy prison sentences in the past month as the Syrian government has reasserted a crackdown on advocates of democratic reform in Syria.