Syrian government forces surrounded a Turkish observation post in the northwest Friday after overrunning nearby areas, a war monitor said, while Ankara vowed not to withdraw from its position.
"Regime forces have surrounded the Turkish observation post in Morek after capturing other towns and villages in this pocket," said the Syrian Observatory for Human Rights.
Speaking at a news conference in the Lebanese capital, Turkey's Foreign Minister Mevlut Cavusoglu said "our observation point there is not cut-off and nobody can isolate our forces and our soldiers."
"We are there, not because we can't leave but because we don't want to leave," he said, adding that the issue was being discussed with Damascus' allies Russia and Iran.
The Syrian regime has upped the stakes with Ankara in its months-long Russian-backed offensive against the jihadist-ruled Idlib region, which borders Turkey.
Moscow said on Friday that it has agreed with Ankara to "activate mutual efforts" to ease the situation in Syria's last major opposition bastion.
Turkey later announced that President Recep Tayyip Erdogan would visit Moscow on Tuesday for talks with his Russian counterpart, Vladimir Putin, a meeting confirmed by the Kremlin.
The town of Morek, where the Turkish troops have allegedly been cut off, lies in the north of Hama province, part of the region centred on neighbouring Idlib province that has been under government assault -- initially by air -- since late April.
Government forces took control of Morek and nearby towns including Kafr Zita on Friday, Syrian state news agency SANA said.
Jihadists and allied rebels withdrew from the area ahead of the Syrian army's entry into the strategic town of Khan Sheikhun on Wednesday and government forces took control without resistance, according to the Britain-based Observatory.
- 'Whatever is necessary ' -
The Morek observation post, established under a deal with Moscow, is one of 12 the Turkish army set up along the front line between Syrian government forces on one side -- and the jihadists and Ankara's rebel allies on the other side -- last year.
On Tuesday Cavusoglu vowed that the Turkish army "will do whatever is necessary" to defend these positions.
The Turkish presidency has also said that it will not abandon any of its observation posts in Syria.
The Turkish troops' mission was to oversee the establishment of a buffer zone agreed by Ankara and Moscow in September.
But the jihadists failed to pull back from the zone as agreed and in April, government and Russian forces resumed intense bombardment of the region.
The Kremlin on Friday said that Russian President Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan agreed to "activate mutual efforts" to ease the situation in the Idlib region.
"They discussed the issues of Russian-Turkish cooperation in the context of stabilisation of the de-escalation zone," a statement said.
Erdogan is to host his Russian and Iranian counterparts for a summit in Ankara next month to discuss the latest developments.
The Turkish presidency on Friday said regime attacks in Idlib have led to a "grave humanitarian crisis".
"These attacks damage the efforts to regulate the Syrian conflict," it said.
The pro-government Al-Watan newspaper on Friday said the latest regime gains in Idlib will force amendments to the buffer zone deal.
- Continued offensive -
Since January, the Idlib region has been ruled by the Hayat Tahrir al-Sham alliance, which is led by jihadists from Syria's former Al-Qaeda affiliate.
Other rebel groups allied with Turkey were forced to cede overall control.
On August 8, Syrian government forces launched a ground offensive with Russian support against the southern part of the rebel-held region, eyeing control of the main highway from Damascus through Idlib province to second city Aleppo.
Khan Sheikhun and Maarat al-Numan both lie along the highway.
The Syrian army on Friday said that its military "push is ongoing," after it captured Morek and neighbouring areas.
"Armed terrorist groups have lost the ability to stop our army's heroes" it said.
Damascus said Thursday it will open a corridor for civilians to leave the area.
But most civilians had already fled before the pocket was cut off, according to the Observatory.
Since the end of April, more than 400,000 people have fled their homes, particularly in the south of Idlib and north Hama, the United Nations says.
Around 900 civilians have been killed, according to the Observatory.
Following a string of victories against jihadists and other rebel groups, Assad's government now controls around 60 percent of Syrian territory.
The war in Syria has killed more than 370,000 people since it started with the brutal suppression of anti-government protests in 2011.