Abd al-Rahman al-Shaghuri was arrested in February 2003 for the electronic mailing of articles he had lifted from a British website which is banned in Syria. He was charged with spreading "false and exaggerated news that sap the morale of the nation".
Amnesty International, which is based in London, called for al-Shaghuri's "immediate and unconditional release". The final hearing in his trial is expected on Sunday in the State Security Court.
Decisions of the court, which was created under Syria's 1963 emergency legislation, cannot be appealed against. Its cases are often heard by military judges.
In a statement on Friday, Amnesty also called for the release of four other detainees who it said have been held "solely for peaceful exercise of their right to free expression over the internet".
Three brothers, Muhannad, Haitham Qutaysh and Yahia al-Aws, have been in detention for more than 18 months on charges of sending false information that threatens state security to an electronic newspaper abroad. Their trial before the court is scheduled for 25 July.
A fifth Syrian, Masud Hamid, has been imprisoned since July 2003 for posting on the internet photographs of a Kurdish demonstration in Damascus.
Anwar al-Bunni, a lawyer and member of the Human Rights Association in Syria, confirmed the imprisonment and charges imposed on the five men. Al-Bunni, who is defending the prisoners, also called for their immediate release.
"[The accused Syrians have been held] solely for peaceful exercise
of their right to free expression over
London-based human-rights organisation
Since he came to power in 2000, Syrian President Bashar al-Asad has passed laws aimed at liberalising the state-controlled economy and introduced cellular phones and the internet.
But he also clamped down on pro-democracy activists, showing there are limits to the dissent that his administration is willing to tolerate.
The state-run media remains tightly controlled and the government bans websites deemed suspicious or offensive.