Fresh appeals have been made for the release of two Syrian archbishops six years on from their disappearance.

Syriac Orthodox Archbishop Yohanna Ibrahim and Greek Orthodox Archbishop Paul Yazigi have been missing ever since they were kidnapped at gunpoint outside Aleppo in April 2013. 

What happened to the men after their abduction remains a mystery.  It is also unknown who was behind the kidnapping as no group has ever come forward to claim responsibility. 

The World Council of Churches has made repeated calls for the archbishops to be released.  In a new commuique, its Permanent Committee on Consensus and Collaboration said the churches in Syria and Lebanon were continuing to suffer as a result of their abduction. 

"In the years since their abduction, the World Council of Churches has expressed its concern and called for the release of the two archbishops of Aleppo," the communique reads.

"There is still no word on the whereabouts and condition of these two archbishops."

The communique was issued during a meeting of the committee this week at St John of Damascus Theological Institute, at the University of Balamand in Lebanon, where Archbishop Yazigi served as dean. 

He was praised in the communique for his work to strengthen the "presence of Orthodoxy not only for Antioch but also throughout the east". 

"Both archbishops demonstrated the love of Christ for all persons without exception, and are considered spiritual Orthodox leaders," the document continued.

It concluded with a call to Christians to continue praying for the safe return of the two church leaders "as a sign of hope for all the Christians of Syria and the region".