A Turkish official, speaking on condition of anonymity, said UN Security Council members China and Russia are also unlikely to attend the meeting despite invitations from the group, while Damascus's close regional ally, Iran, has not been invited.
Ankara says the Syrian opposition is facing an asymmetrical military challenge because Iran and Russia continue to provide arms to President Bashar al-Assad, while the opposition has failed to convince its international backers to do the same for them.
Ankara also believes that Iran transfers arms to Syria via Iraq despite Iraqi statements to the contrary. The official said Iran has been told in diplomatic contexts that it will be on the losing side if it sides with Assad. Aware of the risks that could stem from Assad's fall, Iran is working hard to ensure Assad receives maximum support.