An explosion in the northwestern Turkish city of Bursa was caused by a female suicide bomber, the governor's office said in a written statement.

The blast occurred at the entrance of Bursa's historic UIucami mosque, private Dogan news agency reported.

Thirteen people were wounded in the blast, a medical source said.

Turkey has been hit by a series of suicide bombings this year, including two in Istanbul blamed on Islamic State and two in the capital Ankara claimed by Kurdish militants.