Turkey will not take the "smallest step back" in Syria's last rebel bastion of Idlib, where several Turkish observation posts have been surrounded, President Recep Tayyip Erdogan said on Wednesday.
He said he hoped the issue of using air space in Idlib would be resolved soon. Russia controls the region's air space and bombed Turkey-backed rebels on a daily basis in support of an offensive by Syrian government forces.
"We will not take a smallest step back in Idlib, we will certainly push the regime outside the borders we designated, and ensure the return of the people to their homes," Mr Erdogan told his party's MPs in Ankara.
"We are planning to liberate our observation posts from the surrounding Syrian government forces by the end of this month, one way or another."
As part of its deals with Russia, a key supporter of Syria's President Bashar Al Assad, Turkey has 12 observation posts in Idlib, but several of them have come under fire from regime forces this month.
Ankara has confirmed as many as 17 Turkish security personnel have been killed, which prompted officials to turn to Russia.
Mr Erdogan repeated his call for Damascus to "stop its attacks as soon as possible" and pull back from Ankara's outposts by the end of February.
Syrian rebels backed by Turkey seized the town of Nayrab in Idlib province this week, according to rebel and Turkish sources, but Mr Al Assad's forces continue to make advances elsewhere in the province.
On February 5, Mr Erdogan said Mr Al Assad's forces must pull back behind a line of Turkish observation posts by the end of February, or Turkey would drive them back.
Turkey, which has already taken in about 3.7 million Syrian refugees, says it cannot handle another wave of people and has closed the border.
Syrian government forces are advancing closer to camps for displaced people near the Turkish border and residents fear being caught up in the fighting.
In Geneva, the International Committee of the Red Cross called on the warring sides to allow safe passage for civilians to escape attacks. The group said hospitals, markets and schools were protected by law.
"We are urging parties to allow civilians to move to safety, either in areas they control or across the front lines," ICRC spokeswoman Ruth Hetherington said.
Most of the displaced are cramming in to pockets of territory near the Turkish border. Bitter winter weather has made their plight more desperate, with many camping by roads or in fields due to the lack of shelter.
The regime offensive could mark the final chapter of a war that has killed hundreds of thousands of people, displaced millions and devastated whole cities since an uprising against Mr Al Assad in 2011.
