Twelve Turkish soldiers have died after being exposed to methane gas while searching a cave in Iraq, the Turkish Ministry of National Defence said.

At least 19 personnel were exposed to the gas during the search and clear operation on Sunday, and immediately taken to hospital.

By Monday 12 soldiers had died, the ministry said.

President Recep Tayyip Erdogan said he received the news with “great sorrow” and extended his condolences to the soldiers’ families and to the Turkish Armed Forces.

Methane gas is not directly toxic, but can be deadly as it can become suffocating, especially in tight, enclosed spaces.

The injured soldiers were searching for the body of a soldier who was killed in gunfire in May 2022 during Operation Claw Lock – a military operation led by Turkey against militants from the Kurdistan Workers’ Party (PKK) in Iraq which included air strikes on caves as well as a ground incursion.