So-called Islamic State has released a video online which claims to show two Turkish soldiers being burned alive.
IS claims the video is from its Syrian operation, and shows two soldiers captured in late November. The killing came in revenge for Turkish killing of Muslims, the group said.
Turkey has been fighting IS with both ground forces and air strikes.
The video has not been independently verified. There has so far been no comment from Turkey.
However, Turkish officials did not immediately respond to the publication of the video late on Thursday.
IS released the video through a number of its online accounts and through the messaging app Telegram.
It showed the two men, dressed in camouflage, caged in open countryside. The pair, collared and chained, were taken from the cage and made declarations to camera before being killed.
Several reports suggested that Turkey had limited access to social media sites such as Twitter and YouTube following the release of the footage. However, many users reported no interruption.
Earlier this week, 16 Turkish soldiers died near the northern Syrian city of al-Bab, in the biggest loss for Turkish forces fighting the IS group in the region.
Turkish soldiers have been operating in the area since August.