Eight people have been wounded in a bombing in Turkey's north-western city of Bursa.

A woman blew herself up near the main mosque in the city on Wednesday. There was no immediate claim of responsibility.

Bursa is Turkey's fourth-largest city, an industrial hub south of Istanbul across the Marmara Sea. The attack happened a day after the United States warned American citizens in Turkey about credible terrorist threats to tourist areas.

Turkish Prime Minister Ahmet Davutoglu has claimed no evidence for the warning.

He said, "Tourists visiting Paris or Brussels do not face less risks than those visiting Istanbul or Bursa. Terror is a universal threat and we should be vigilant everywhere.

But we should not create an atmosphere of panic, as the terrorists want. Such an atmosphere of panic can be prevented through the joint efforts of the international community. Therefore, I would like to say that I don't find these warnings right within this framework."