Turkey's defense chief said Sunday that his country's troops won't evacuate their 12 observation posts in rebel-held northwestern Syria. That's even as a Syrian government offensive pushed deeper into Idlib province, the last remaining opposition stronghold.

Turkey — a strong backer of some of the rebels fighting Syrian President Bashar Assad's forces — has a dozen observation posts in Idlib province, as part of an agreement reached last year with Russia, a main supporter of Assad.

Last week, Syrian troops surrounded a Turkish observation post outside the village of Surman, according to the Britain-based Syrian Observatory for Human Rights, an opposition war monitor.

"We will in no way evacuate or abandon the 12 observation points where our soldiers are heroically and with devotion fulfilling their duties to ensure a cease-fire," said Turkey's Defense Minister Hulusi Akar, as quoted by the the state-run Anadolu Agency. "We will continue to remain there."

Akar also called on Russia to use its influence to stop the Syrian government offensive. He spoke while inspecting troops near Turkey's border with Syria.

After weeks of intense bombardment, Syrian government forces launched a ground offensive into the southern and eastern parts of Idlib province this month, forcing tens of thousands to flee their homes. The attacks resumed after a cease-fire in place since the end of August collapsed.

Relations between Turkey and Syria have deteriorated sharply since the conflict in Syria began in 2011. Damascus accuses Ankara of undermining its security by allowing thousands of foreign fighters to cross the border into Syria.

Idlib province, which is dominated by al-Qaida-linked militants, is home to 3 million civilians. Many were already displaced by previous rounds of violence.

The United Nations has warned of the growing risk of a humanitarian catastrophe along the Turkish border. Many displaced civilians have apparently moved close to the border but have not entered Turkey.

Akar said that some 280,000 people fled their homes in Idlib in recent weeks as a result of the offensive. The U.N. humanitarian agency has put the number of displaced at more than 235,000 people between Dec. 12 and Dec. 25.

"If this pressure continues, it will create another important refugee influx. This additional burden will be too heavy for Turkey, which hosts around 4 million Syrian brothers. Therefore, we are doing all we can to prevent this migration," Akar said.

The International Rescue Committee said Saturday that conditions in the province were at a breaking point.