“Our situation as prisoners of conscience is part ... of the crisis of public freedoms and human rights in Syria, which started with the state of emergency imposed 44 years ago,” they said in a joint letter from Adra prison near Damascus.

“The crisis has reached its climax today, with increased repression and suppression of freedoms,” they wrote in the letter published in Lebanon’s leading An-Nahar newspaper.

The signatories are Anwar Bunni, Michel Kilo, Kamal Labwani, Mahmud Issa, Faeq al-Mir and Aref Dalila. The newspaper did not disclose how the letter was smuggled out of the Syrian prison.

The six opposition figures called for “solidarity” with rights activists jailed in Syria, which has been under a state of emergency ever since the Baath party seized power in 1963.

“The detainees should feel that they are not alone... and that there is hope for a peaceful resolution of the crisis of freedoms and human rights in Syria,” they said.

“The Syrian people are paying a heavy price in order to obtain their rights, and we hope that we are the last payment of this expensive price in order for the Syrians to regain their freedoms,” they said.