An explosion killed at least 10 people and injured 15 others on Tuesday in a historic district of Istanbul popular with tourists, the Istanbul governor's office said. At least six Germans were among the wounded, a news agency reported.

The cause of the explosion in the Sultanahmet district was being investigated, but state-run TRT television reported it was likely caused by a suicide bomber. A government official, speaking on condition of anonymity, said the explosion was believed to be "terror-linked".He did not provide further details.

Omer Celik, the spokesman for Prime Minister Ahmet Davutoglu's ruling party issued a statement condemning what he called "a heinous attack".