Fourteen Turkish soldiers have been killed in fierce fighting against so-called Islamic State in Syria, the Turkish army said.
Wednesday's clashes happened in the town of al-Bab, which Turkey is helping rebels take from IS control.
A further 33 Turkish soldiers were reported wounded.
It is the Turkish military's biggest loss in a single day since launching its military operation in Syria in August.
The army said IS used multiple suicide bombs, with 138 IS fighters killed in the fighting. This toll could not be verified independently.