ISTANBUL – At least 29 Turkish soldiers were killed in Syria’s embattled Idlib province late Thursday in a Syrian government airstrike, the governor of Turkey’s nearby Hatay province said.

The strike is a sign of the increasingly volatile situation in Idlib and the escalating tensions between the Turkish and Syrian forces there.

The death toll was the highest for Turkish forces in a single day since Turkey began ramping up the deployment of troops to Idlib this month. At least 36 Turkish soldiers were also wounded, according to Hatay Gov. Rahmi Dogan.

Earlier Thursday, Turkish President Recep Tayyip Erdogan said three Turkish soldiers had been killed in Idlib. It was not clear whether those deaths were included in the total cited by the governor.

Erdogan convened an emergency meeting of his top security officials Thursday night, according to local media, amid unconfirmed reports that the Turkish death toll was even higher. The Syrian Observatory for Human Rights, a monitoring group, said 34 Turkish soldiers had been killed.

The SOHR, as well as the Hatay governor, said the attack on the Turkish troops had occurred in southern Idlib province, where Turkey maintains military observation posts.

Turkey has been trying to halt a rapid advance by the Syrian army across Idlib province and nearby areas, which have been held by rebels opposing the government of Syrian President Bashar Assad.

The Syrian offensive has sparked a humanitarian crisis and sent hundreds of thousands of displaced Syrians fleeing toward the Turkish border. Russia, which is the Syrian government’s principal ally, has provided military support for the Syrian advance.

The Turkish government has called for the restoration of a deescalation agreement between Ankara and Moscow and threatened to take further military action if Syrian forces do not withdraw from areas they have captured in Idlib.

Negotiations between Turkey and Russia over the past month have repeatedly faltered as the humanitarian crisis has worsened and the Turkish death toll has steadily risen. Before the deaths announced Thursday, at least 18 Turkish soldiers had been killed in Idlib, according to a tally by The Associated Press.

The Trump administration has voiced support for Turkey, its NATO ally as Erdogan’s government wades deeper into the Syrian war. Ankara has asked Washington to provide Turkey with the Patriot air defense system, but the Trump administration has refused because of Turkey’s purchase of a Russian missile defense system.

Kay Bailey Hutchison, the U.S. ambassador to NATO, said during a briefing with reporters at the State Department on Thursday that she was unaware of the reports of large-scale Turkish casualties but called it a “big development.”

“I hope that president Erdogan will see that we are the ally of their past and their future. And they need to drop the S-400,” she said, referring to the Russian missile defense system.

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Hudson reported from Washington.