yria's transitional President Ahmed al-Sharaa and Turkish President Tayyip Erdogan are expected to discuss a joint defense pact in Ankara on Tuesday, including establishing Turkish airbases in central Syria and training for Syria's new army, four sources familiar with the matter said.

NATO member Turkey has long backed Syria's armed and political opposition to ousted leader Bashar al-Assad, who was toppled in late December in a lightning offensive spearheaded by Sharaa's forces.

Ankara is positioning itself to play a major role in the new Syria, filling a vacuum left by Assad's main regional backer Iran, in an expansion of Turkish sway that could spark rivalry with Gulf Arab states and put Israel on edge.

The sources - a Syrian security official, two Damascus-based foreign security sources and a senior regional intelligence official - spoke on condition of anonymity as they were not authorised to speak to the media about the meeting.