Bishop Selwanos Boutros Alnemeh of Homs and Hama has repeated an appeal for the release of 12 women religious kidnapped in Syria on 2 December.
The nuns are Sisters from the Convent of St Tekla in Maalaoula, a largely Christian town north of Damascus. Pope Francis also appealed this past weekend for their freedom.
Speaking in an interview with the Catholic charity Aid to the Church in Need, Syrian Orthodox Bishop Alnemeh said that he had not heard from the Sisters since their disappearance 10 days ago.
He said he believes that the women are now being held in Yabrud, which is 12 miles from Maaloula.
The bishop declared: "I demand the immediate release of the nuns, who have done no harm to anyone. We've reached the point where even nuns are being abducted. What have they done wrong? It's a crime. The abductors want to demonstrate that they know no mercy.
"[The Sisters] were neither on the side of the regime nor on that of the opposition. In the convent they took in war refugees without regard for their religion including Muslims.
Melkite Greek Catholic Gregorios III of Antioch also appealed for the release of the nuns. He said that they should be returned without delay to the care of Greek Orthodox Patriarch John X of Antioch.
Both Patriarch Gregorios and Bishop Alnemeh said that there was still no further news of the whereabouts of Patriarch John X's brother, Archbishop Paul Yazigi and Archbishop John Ibrahim, who were both abducted in April 2013 while returning to Aleppo.
Bishop Alnemeh said that Christians had been particularly harmed by the conflict in Syria. He said that in his episcopal city of Homs, 3,000 Christians had died. A further 100,000 had been forced to flee and many churches had been destroyed, he said.
Syrians are tired of war, he added: "The Syrian people no longer believe that this is revolution or reform, or the setting up of a new state on a clear foundation."
Many Christians and others in Syria are hoping that the Geneva II peace conference in January 2014 can produce a breakthrough to the conflict, and some hope of justice and peace for a deeply troubled land.