Three Turkish soldiers have been killed and 10 others wounded in northern Syria in a Syrian government air strike, the Turkish military says.

The attack occurred at about 03:30 (00:30 GMT) on Thursday, during an operation by Turkish-backed Syrian rebels against Islamic State militants.

It would be the first time Turkish soldiers have been killed by Syrian government forces in the offensive. There was no immediate comment from the Syrian military. It has previously denounced Turkey’s support for the rebels with hundreds of troops, warplanes, tanks and artillery as a “flagrant violation of Syrian sovereignty”.

The rebel offensive, dubbed Operation Euphrates Shield, was launched three months ago with the aim of pushing IS militants away from the Turkish border.

The Turkish government also wants to contain US-backed Syrian Kurdish Popular Protection Units (YPG) militia, which it says is an extension of the outlawed Kurdistan Workers’ Party (PKK) in Turkey.

So far, the rebels have driven IS militants out of more than 1,800 sq km (694 sq miles) of territory, according to the Turkish military, and recaptured the key border town of Jarablus and the symbolically important village of Dabiq. They are now besieging the town of al-Bab, the last IS stronghold in Aleppo province. The Turkish soldiers killed overnight were deployed close to al-Bab when they were targeted by Syrian government aircraft, the state-run Anadolu news agency said. The dead and injured, one of whom was said to be in a critical condition, were taken to hospitals in the southern Turkish provinces of Kilis and Gazientep. The deaths mean that at least 15 Turkish soldiers have been killed since Operation Euphrates Shield began, according to AFP news agency. Most died in clashes with IS, but one was killed in an attack blamed on the YPG.