At least 34 Turkish soldiers were killed after an airstrike on Thursday by Syrian government forces in Idlib, Syria.
According to the BBC, several more soldiers were injured.
Turkey's losses come over an escalating confrontation between Russian-backed Syrian government forces and Turkish-backed rebels, who have been in heavy clashes for the key town of Saraqeb in the past few days.
Turkish soldiers were reportedly in the region to support the Syrian rebels.
The BBC reports, these latest strikes against Turkey come after Turkish-backed rebels recaptured the town of Saraqeb from Syrian government forces on Thursday.
Turkish President Recep Tayyip Erdogan speaks to his ruling party members, in Ankara, Turkey, February 27, 2020. /AP
Idlib is Syria's last rebel-held stronghold.
Erdogan convened an urgent security meeting late Thursday over the attack on Turkish troops.
The Russian defense ministry on Thursday accused Turkey of violating a peace deal for Syria's Idlib by supporting rebels with artillery fire and drones.
"In violation of the Sochi agreements in the Idlib de-escalation zone the Turkish side is continuing to support illegal armed groups with artillery fire and the use" of drones to target the Syrian troops, the ministry said, quoting the head of the Russian Reconciliation Center for Syria, Oleg Zhuravlev.
Turkish and Russian delegations were on the second day of talks in Turkey's capital Ankara on Thursday aiming to reach a truce in the last rebel stronghold Idlib.
Turkey-backed Syrian rebels enter the own of Saraqeb, in Idlib province, Syria, February 27, 2020. /AP
Turkey emphasized the need for a ceasefire in Syria's northwest Idlib province and what steps are needed on the ground to achieve it during talks with a Russian delegation on Thursday, the Foreign Ministry said.
Turkey also stressed the need to head off a possible humanitarian catastrophe and mass migration from Idlib, the Turkish ministry said following the meeting in Ankara.
(with input from agencies)