Christian Solidarity Worldwide has condemned the kidnapping of two senior church leaders in Syria.

Archbishop Boulos Yazigi of the Greek Orthodox Church and Archbishop Yohanna Ibrahim of the Syriac Orthodox Church were abducted by gunmen on Monday evening from the village of Kfar Dael.

The bishops were returning to Aleppo after overseeing a humanitarian effort close to the Turkish border when their vehicle was intercepted. Their driver was killed in the incident.

It is not clear who was behind the kidnapping.

Reuters cited a church official who said the men had been released on Tuesday, but there is confusion over whether this is the case.

Abductions have been a feature of the conflict in Syria but this is the first time such senior church figures have been targeted.

CSW warns that the abduction is likely to heighten concerns amongst Syria's Christian society regarding their future.

The CSW is part of the Religious Liberty Partnership which just last week urged the United Nations Special Envoy for Syria to pay particular attention to "vulnerable" ethnic and religious minorities.

CSW's Chief Executive Mervyn Thomas said, "CSW is deeply concerned by these kidnappings and our thoughts and prayers are with both men and also with Syrian Christians, who must be deeply disturbed and discouraged by these developments.

"We urge key members of the international community, and particularly those belonging to the 'Friends of Syria' group, to make urgent representations to ensure these men are released swiftly and unharmed, and to encourage every party to the conflict to adhere to humanitarian standards with regard to the treatment of civilians, religious leaders and religious establishments, regardless of creed or ethnicity."