Ten policemen were among the dead in the attack, which occurred about 11 am, according to a police official in the city who spoke

on condition of anonymity because he was not authorised to release the information.

Fallujah, in restive Anbar province, is 65km west of Baghdad.

Police said the bomber detonated his explosives vest at the third of four checkpoints as he stood among recruits who were lining up to apply for jobs on the force. The centre had only been opened on Saturday in a primary school in eastern Fallujah.

The US military and Iraqi army and police were running the centre along with members of Anbar Salvation Council, a lose grouping of Sunni tribes that have banded together to fight al-Qaeda.

Police stations and recruiting posts have been a favourite target of Sunni insurgents and al-Qaeda through the course of the Iraq war.

Meanwhile, six more US soldiers have died in attacks across Iraq this week, the US military reported on Thursday, cementing May's position as the deadliest month of the war since 2004.

Two soldiers died in a roadside bomb explosion on Wednesday while patrolling the dangerous neighbourhoods in the southwest corner of the capital, which have seen intense fighting in recent days.

Another two were killed by a roadside bomb during a foot patrol the same day, the military said in a statement without specifying the exact location.

Another soldier was seriously wounded following a roadside bomb explosion northwest of the capital on Monday, and died in a combat support hospital the next day, with the military announcing the death on Thursday.