A Turkish police officer and a courthouse employee were killed by a car bomb in the Aegean coastal city of Izmir on Thursday (January 5), a police source said.

Police shot dead two attackers and were searching for a third after the explosion outside an Izmir courthouse, state media and local officials said.

At least 10 wounded people were taken to hospital and some of them are said to be in a critical condition.

One unidentified witness described the attack, which he said happened when a car was deliberately driven into a policeman and "crushed" him.

The bombing comes less than a week after a gunman shot dead 39 people at a nightclub in Istanbul on New Year's Day in an attack claimed by Daish.

The gunman is still at large.

Police detained 20 suspected Daish militants thought to be of Central Asian and North African origin in Izmir on Wednesday, in raids Turkish media said were linked to the Istanbul nightclub attack.

Turkey faces multiple security threats. It has been hit by a series of bombings over the past 18 months, some of them blamed on Daish, others on Kurdish militants.