The meeting of foreign ministers was originally called for Monday by Riyadh, which backs militant groups in the conflict, to discuss "steps that need to be taken to deal with the Syrian tragedy".

But the Saudis have now indefinitely postponed what was originally billed as an emergency gathering that they were going to host without saying why, and no new date has been set for it.

Western and Persian Gulf nations opposed to the legal Syrian government of President Bashar al-Assad are due to hold their latest meeting in London on May 15 to discuss boosting support for the foreign backed militant groups.

More than 150,000 people are estimated to have been killed in Syria since the start of the foreign backed armed uprising against Assad's rule in 2011.

UN-Arab League mediator Lakhdar Brahimi said in late March that a resumption of peace talks in Geneva between Damascus and the opposition was currently "out of the question".

Assad's government is preparing for a presidential election on June 3 which excludes the exiled militant groups’ leaders.

NJF/NJF