Human Rights Watch has called on Syrian president Bashar al-Assad to release one of his most outspoken critics, prominent lawyer Haitham al-Maleh who turned 80 in jail on Sunday.
A military court sentenced Maleh to three years in July on charges of "weakening national morale".
He was arrested last year after he stepped up his criticism of corruption in Syria and called on Assad to repeal emergency laws and reveal the fate of tens of thousands of people missing since the government, controlled by the Baath Party since 1963, violently crushed its opponents in the 1980s.
"President al-Assad surely cannot justify keeping behind bars an 80-year-old man who is only in jail for speaking his mind," said Joe Stork, deputy Middle East director of the New York based group.
"President al-Assad should show compassion during this month of Ramadan and release Haitham al-Maleh,"
Stork said in a statement sent to Reuters.
Human Rights Watch said that according to Maleh's son, Maleh's health was deteriorating and his ailments included degenerative arthritis.
Maleh, a former judge, spent six years as a political prisoner in the 1980s during the reign of Assad's father, the late Hafez al-Assad, after he opposed what he described as the illegal takeover by the Baath Party of the judiciary and the Lawyers Union.
As a lawyer, he spent his professional life defending political prisoners.
In 2006 he was awarded the Dutch Geuzen medal, named in honour of resistance fighters against the Nazis, for his defence of liberty. Banned from leaving Syria, he could not collect the prize.
The United States has been at the forefront of international calls to release Maleh and scores of leading Syrian writers, journalists, opposition figures and lawyers who have been jailed in the last five years, despite Syria's rehabilitation in the West and better relations with Washington.
