As reported by Censor.NET citing The Wall Street Journal, the military general staff in Ankara said in a statement, without specifying the area that was bombed or providing additional details.
It was the first deadly airstrike on Turkish forces since the country launched an operation against Islamic State in August.
Syrian authorities weren't available to comment on Turkey's charge, but a senior U.S. official said the American-led military coalition battling Islamic State had confirmed the soldiers were killed by a regime airstrike.
The Syrian Observatory for Human Rights, a U.K.-based monitoring group, earlier challenged Turkey's claim, saying its information pointed to a suicide bombing on Wednesday by Islamic State-which claimed via its media arm to have attacked a Turkish command center in Syria.
"Clearly, there are those who are not happy with Turkey's fight against Daesh," Turkish Prime Minister Binali Yildirim said Thursday afternoon in Ankara, referring to Islamic State by its Arabic acronym. "There will certainly be retaliation against these attacks."
The allegation comes as Syrian rebels backed by Turkish forces have expanded their control in northern Syria to a 700-square-mile area and advanced on the Islamic State-held town of al-Bab, which sits just 25 miles east of Aleppo, the key battleground between opposition and regime forces.
The development threatens to stoke tensions among the players in Syria's multifaceted war. A direct confrontation between Syria and Turkey risks yet another row with Russia, which supports Syrian President Bashar al-Assad, whom Ankara opposes.
It comes exactly a year after Turkey became the first NATO member since 1952 to down a Russian jet, saying the plane violating its airspace from Syria, a move that triggered a war of words and prompted sanctions by Moscow.
Normalization of bilateral ties with Russia has allowed Turkey to flex its military muscles, resuming airstrikes inside Syria.
Turkey launched its military offensive inside Syria on Aug. 24, seeking to oust Islamic State from a 60-mile stretch of the border days after blaming the group for a deadly bombing in the border city of Gaziantep.
The campaign, called Operation Euphrates Shield, quickly expanded to also counter U.S.-backed Syrian Kurdish forces, which Turkey considers a terrorist organization. Last month, Turkish jets struck Syrian Kurds competing with Ankara-backed rebels to control a region north of Aleppo.
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