UNITED NATIONS, Sept. 18 (Xinhua) -- UN Secretary-General Antonio Guterres on Tuesday welcomed the Russia-Turkey agreement to create a demilitarized buffer zone in Syria's Idlib region, which he said should avert a full-scale military operation and provide reprieve for millions of civilians.

The secretary-general calls on all the parties in Syria to cooperate in the implementation of the agreement and ensure safe and unimpeded humanitarian access in all areas through the most direct routes, said Stephane Dujarric, Guterres' spokesman, in a statement.

Guterres also stresses the need for swift action to address the root causes of the conflict and forge a durable political solution, said the statement.

Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan agreed on Monday to establish a demilitarized zone within Idlib province, the last major rebel stronghold in Syria.