Iraqi police Lieutenant Colonel Zakariah al-Juburi said two Iraqi policemen were wounded in the blast, which targeted an American patrol.

The US military considers the volatile city to be the last urban stronghold of Al-Qaeda in Iraq, which has been driven out of vast swathes of the country by US and Iraq forces, including allied local Sunni militias.

At least 4,209 US soldiers have died in Iraq since the 2003 invasion to topple Saddam Hussein, according to an AFP count based on the independent website www.icasualties.org.

Earlier on Thursday 15 people were killed and 147 others wounded when two suicide vehicle bombs targeting police posts exploded in Fallujah, a former Sunni insurgent bastion that has seen few attacks in recent months.

The total number of bombings in Iraq has plummeted over the past year as US and Iraqi forces have flooded into former insurgent and militia strongholds, but the country still sees near-daily attacks.