President Recep Tayyip Erdogan on Wednesday threatened to launch an operation in Syria's Idlib region by the end of the month if Syrian forces fail to withdraw behind Turkish military positions.
"As with all [previous] operations, we say 'we could suddenly come one night.' In other words, an Idlib operation is a matter of time," President Erdogan told his party's parliamentary group in the capital Ankara, according to the state-run Anadolu Agency.
"An operation in Idlib is imminent … We are counting down, we are making our final warnings," he said.
Turkey is determined to transform Syria's Idlib into safe place both for Turkey, and the region's people at any cost, Mr Erdogan said.
Russia warned Turkey against attacking Syrian forces, with Kremlin spokesman Dmitry Peskov saying an operation against "the legitimate authorities of the Syrian republic and armed forces" would be "the worst scenario".
It comes as Syrian aid workers issued an urgent call for a ceasefire and international help for nearly a million people fleeing a regime onslaught in Syria's north-west.
At a press conference in Istanbul, the Syrian NGO Alliance said existing camps are overcrowded and civilians forced to sleep in the open as more than 900,000 people flee the violence.
"We are facing one of the worst protection crises and are dealing with a mass movement of IDPs (internally displaced persons) who have nowhere to go," the Syrian NGO Alliance said in a statement.
They are "escaping in search of safety only to die from extreme weather conditions and lack of available resources," it added.