The United Nations Special Envoy for Syria called on Wednesday for an immediate end to hostilities along its border with Turkey, where Ankara has launched an assault and Damascus advanced its forces after US troops pulled out.
Geir Pedersen raised Turkey's week-old incursion into northeastern Syria in talks in Damascus Syria's Foreign Minister Walid al-Moualem.
Pedersen told Reuters TV the UN was extremely concerned about the humanitarian consequences of the crisis and called for an "immediate cessation of hostilities".
Moualem was quoted by state news agency SANA as saying Turkey's aggression was prolonging the crisis in Syria and undermining efforts to secure a political settlement.
Pedersen's trip had been planned to discuss preparations for the first meeting of Syria's Constitutional Committee, due to take place in Geneva on Oct. 30.
A congress convened by Russia, a leading ally of Syrian President Bashir al-Assad, has asked the United Nations to form the 150-member committee to draft a new constitution after many rounds of talks to end the war had failed.