BAGHDAD, Sept 14: At least 73 people were killed on Tuesday in a Baghdad car bombing and in an ambush on police in Baquba, claimed by Al Qaeda-linked militants, as fighting flared between US troops and militants in Ramadi.

Fifty people perished in Baghdad, 47 of them when a vehicle packed with explosives blew up outside the police headquarters. More than 100 people were wounded in the bombing, the most lethal in the country for two months.

Shrapnel tore the crowded district, littering body parts everywhere and leaving pools of blood on the pavement. "More than 200 people were queuing outside the main gate. I came with six friends and now I'm alone. They've gone, all of them," said police recruit Nabeel Mohammed, slightly wounded in the blast.

Anguished relatives, seeking news of loved ones, frantically turned over ID cards or inspected dozens of pairs of shoes lined up on the roadside by police near the crater gouged in the ground by the blast.

Interior Minister Falah al-Naqib blamed the bombing on "Arab groups" as angry men cursed US President George W. Bush. Further north in the Sunni Muslim hot spot of Baquba, 13 people died in an ambush, all but one of them a policemen.

Six coalition soldiers have been killed in Iraq over the past 24 hours - including three Poles and three Americans - bringing the US death toll in Iraq to more than 1,012, according to the Pentagon.

Using an Islamist website, the military wing of Zarqawi's Tawhid wal Jihad group purportedly claimed to have orchestrated what it called a suicide bombing in Baghdad and the Baquba gun attack.

"Heroes of the Tawhid wal Jihad are striking with an iron hand anyone who betrays religion and honor," said one of two statements, whose authenticity were impossible to confirm.

US forces have retentlessly pounded alleged Zarqawi safehouses in the restive Sunni Muslim stronghold of Fallujah, but on Tuesday lifted their siege on the northern town of Tall Afar, a suspected staging post for foreign fighters.

Out west, 10 people were killed and 22 wounded in clashes between US troops and militants in Ramadi, where the sound of gunfire echoed from the city centre, the health ministry said.

In the north, insurgents sabotaged a key pipeline, halting oil exports to Turkey, while a second act of sabotage slashed power in Kirkuk and Baiji. Separately the US military reported a fire along a pipeline near the oil refinery town of Baiji, southwest of Kirkuk, in the early hours of Tuesday.

The attack forced the Baiji power plant to shut down, affecting power in both Baiji and Kirkuk. Militants meanwhile claimed two separate kidnappings of a Jordanian and two Turkish truck drivers.

A group calling itself "Squads of Unification Lions" abducted the Jordanian and threatened to kill him unless his employer pulls out of Iraq. For its part, Canberra has vowed never to bow to terrorists amid claims that Iraqi militants have kidnapped two Australians and will execute them unless it withdraws its troops from Iraq. -AFP