The agency quoted unidentified police officials as saying the blast was caused by plastic explosives loaded onto a street vendor's cart and tied to gas canisters.

Citing witnesses, the NTV news channel said unidentified assailants rolled the cart down a hill towards the police building.

The cart hit a parked van before reaching the building and exploded, blowing out the windows of nearby vehicles and buildings, the television report said.

A 54-year-old man who was cleaning a coffeehouse nearby sustained slight injuries to his arm.

Police suspected the outlawed Kurdistan Workers' Party (PKK), which has been fighting the Turkish government since 1984 for self-rule in the mainly Kurdish southeast of the country, of being behind the blast, Anatolia said.

Izmir, which lies on the Aegean coast and is the country's third-biggest city, has been the target of bomb attacks by Kurdish rebels fighting the Turkish government.