The explosion ocurred at the entrance of a building housing shops and business offices in the ancient city of Mardin, they said.

It appeared to have been caused by a gas ganister, but police have not ruled out the possibility of a bomb attack.

The blast sparked a fire, which burnt down five shops and damaged five others, before being extinguished by firefighters, Anatolia news agency reported.

Violent incidents are frequent in Turkey's southeast, where the rebel Kurdistan Workers' Party (PKK) has waged a bloody 24-year campaign for Kurdish self-rule.

The PKK, listed as a terrorist group by Ankara and much of the international community, has carried out bomb attacks in the southeast in the past, targeting mostly the security forces.