At least 22 Turkish soldiers were killed in the northwestern Syrian province of Idlib after an airstrike on Thursday blamed on Damascus, as violence escalated in the already chaotic region.
Several soldiers were injured and taken to Turkey for treatment, Rahmi Dogan, the governor of Hatay in Turkey, which sits on the border with Syria, said in televised remarks early Friday.
Counting those lost in the latest attack, 42 Turkish security personnel have been killed in Idlib.
The losses came after weeks of growing tensions between rebel supporter Ankara and Damascus ally Moscow.
Turkey has urged the Syrian regime to withdraw from Turkish observation posts in Idlib, while Moscow has accused Ankara of aiding "terrorists" in Syria.
Under a 2018 deal with Russia meant to bring calm to Idlib, Turkey has 12 observation posts in the region, but several have come under fire from Syrian President Bashar al-Assad's forces.
Erdogan calls meeting
Turkish President Recep Tayyip Erdogan hastily convened an emergency meeting in Ankara after the attack in Idlib, attended by the defense and foreign ministers as well as the spy chief and military commanders.
There appeared to be restricted access to Twitter, Instagram and other social media, after users in Turkey reported they were unable to use the websites.
Jihadists and Turkish-backed rebels on Thursday re-entered Saraqeb, a key crossroads town in Idlib they had lost earlier in February, reversing one of the main gains of the government's devastating offensive.
The counteroffensive could, however, be short-lived as Russian-backed Syrian troops continued to chip away at other parts of the rebel bastion, capturing 20 localities as Damascus ignored growing international appeals for a cease-fire.
Seven civilians, including three children, were killed in regime and Russian bombardment of Idlib, according to the Syrian Observatory for Human Rights, adding to more than 400 civilian deaths since December.
The U.N. Security Council, where Moscow has systematically vetoed truce initiatives, met again on Thursday amid growing concern that Idlib is witnessing the nine-year-old war's worst humanitarian emergency.
State news agency SANA acknowledged that there were "fierce clashes" between the army and "terrorist groups on the Saraqeb front."
An AFP correspondent accompanied the rebels into Saraqeb, where he found a ghost town of bombed-out buildings deserted of inhabitants.
Control of key highway sought
The counterattack temporarily reversed one of the key gains notched up by the government since the launch of its offensive against the country's last rebel enclave in December.
The cash-strapped government had been keen to fully secure the M5, a highway that connects Syria's four main cities and passes through Saraqeb.
The Syrian Observatory said the airstrikes were carried out by Russia, which has come under heavy Western criticism for the high civilian death toll from its bombing campaign.
State media accused the "terrorists" of launching car bombings and other suicide attacks against government forces attempting to retake the town.
It said that the army had inflicted heavy losses on the attackers, despite the military support it said they had received from neighboring Turkey.
Some 950,0000 civilians have fled the government offensive, raising fears in Ankara of a new mass influx of refugees.
3.6 million refugees
Turkey already hosts the world's largest number of Syrian refugees with around 3.6 million people, placing an increasingly unpopular burden on public services.
More than half a million of those displaced since December are children, tens of thousands of whom are sleeping rough in the harsh winter of northern Syria.
The Turkish president vowed Wednesday that Ankara would not take the "smallest step back" in the standoff with Damascus and Moscow over Idlib.
Erdogan warned the Syrian government to "stop its attacks as soon as possible" and to pull back by the end of the month.