During the phone call, Fidan told his US counterpart that Turkey was "against any development that would increase instability in the region and supports efforts to reduce tensions in Syria," according to a Turkish foreign ministry source.

The Turkish foreign minister also stressed that "the political process between the regime and the opposition must be finalized" to ensure peace and security in Syria, while insisting that Ankara "will never allow terrorist actions against Turkey nor against Syrian civilians."

A coalition of Islamist-led rebel groups launched an offensive on 27 November against government forces backed by Russia and Iran in northwest Syria, seizing dozens of towns before reaching Aleppo, the country's economic centre.

Pro-Turkish factions in northern Syria also attacked government soldiers and Kurdish fighters over the weekend in Aleppo province, according to the Syrian Observatory for Human Rights.

The Kurdish People's Protection Units (YPG), considered by Ankara to be an offshoot of the Kurdistan Workers' Party (PKK), have been banned.