Turkey's defence ministry said the explosion occurred "while firing heavy weapon ammunition" at the base in Sungu Tepe in the Hakkari province near Turkey's borders with Iraq and Iran.

Twenty-five soldiers were hospitalised, but officials did not give details on the severity of their injuries. Seven soldiers were missing, the ministry said.

The government has launched an investigation.

The provincial government of Hakkari said in a statement that "defective" ammunition exploded during artillery fire.

It was not clear whether this happened during a combat mission, or an exercise.

Turkey's predominantly Kurdish southeast has seen years of violent fighting between the Turkish army and the Kurdistan Workers Party (PKK), classified a "terrorist" group by Ankara and its Western allies.

Turkey also regularly bombs PKK bases in northern Iraq.

After a brief truce, fighting resumed in 2015, shattering hopes for a peaceful resolution to a conflict that has claimed more than 40,000 lives since 1984.