An initial investigation at the site of the explosion, which occurred minutes after midnight in the Asian part of the city, failed to produce a definite conclusion. The city's police chief, Celalettin Cerrah, said there was no evidence that it was a bomb attack.

"This area does not seem to be a target for terrorists," he said, raising the possibility of an explosion in the fuel tank of a vehicle. A local police official said the blast "might have been the result of a traffic accident."

A woman and her 21-year-old daughter were killed in the blast, which some reports say occurred in a moving vehicle, while others state it was hidden in a garbage can, and exploded as they were leaving a wedding party in a nearby restaurant.

Police have cordoned off the area, where the blast shattered the windows of residential buildings and damaged nine cars, sending panicked residents into the streets in the middle of the night.

String of attacks

A series of explosions, one of them a deadly bomb attack, have hit Turkey over the past month. Most recently, nine people were injured on Tuesday, when two small blasts of unknown cause ripped through garbage cans in the popular Mediterranean resort of Antalya.

The incident followed the bombing of a bus in the seaside resort of Kusadasi on July 16, which killed five people, among them a British woman and an Irish teenager.

The police blamed that attack on the Kurdistan Workers' Party (PKK), an armed rebel group branded as terrorists by the United States and the European Union, which has recently stepped up anti-government violence.

Earlier in July, some 20 people were injured when a bomb planted in a dustbin in another resort, Cesme, went off. The attack was claimed by a little known Kurdish group which the police say is a cover for PKK attacks on civilians.

Islamic extremists and far-left underground groups have also carried out bomb attacks in Turkey. In the deadliest attack in the country so far, 63 people were killed in two sets of twin suicide bombings in Istanbul in November 2003, blamed on a local cell of the al-Qaeda extremist network.