BAGHDAD, Feb 10: A suicide bomber driving a truck full of explosives killed at least 55 people on Tuesday outside a police station south of Baghdad, amid warnings that the Al Qaeda terror group was seeking to spark a civil war.

The dead and wounded were mainly civilians who had flocked to the station in the town of Iskandariya, 45km from Baghdad, seeking jobs as policemen, Iraqi officials said.

The head of Iraq's police force, Lt-Gen Ahmed Kazem Ibrahim, said the attack, the third deadliest in post-war Iraq, was carried out by a foreign suicide bomber driving a pick-up.

Brig-Gen Mark Kimmitt, deputy operations director for the US-led coalition in Iraq, estimated the truck was loaded with 500 pounds of explosives. He said the attack bore "some of the fingerprints" of Al Qaeda but that it was too early to single out suspects.

General Ibrahim said "it can only be foreigners, because the operation targeted only Iraqi civilians." Top coalition civilian spokesman Dan Senor said "Al Qaeda forces feel threatened by the growing Iraqi security services and their increasing effectiveness and by the process by which we are handing over sovereignty to the Iraqi people."

The attack is the most violent against a police station since US President George W. Bush declared major operations over on May 1 of last year, but Ibrahim said only four policeman were wounded.

He said the casualties were civilians volunteering for the new police force and others who were working in or visiting nearby public administration buildings or living in the area.

Coalition forces reported no casualties. The attack came as US officials have been warning against what they describe as an Al Qaeda plot to spark civil war between the Shias and the Sunnis.

Iskandariya is a mixed Shia-Sunni town, and several of those killed were Sunnis, according to an AFP photographer. The explosion at 9:30am left a large crater approximately 25 metres from the police station. -AFP