A suicide bomber killed five US soldiers and two Iraqi policemen when he rammed his explosives-laden truck into a sandbagged wall surrounding a police headquarters in Mosul.

A sixth US soldier and 17 Iraqi policemen were wounded in the blast near the national headquarters in the country's north. Mosul is Iraq's third-largest city and al-Qai'da's last urban stronghold. Suicide bombings continue to threaten the city, which US troops must leave by 30 June under an agreement with the Iraqis.

The approaching deadline has raised fears about what will happen after the soldiers depart. Lt-Col Michael Stuart, the chief of US operations in Tikrit, north of Baghdad, said the US patrol happened to be outside the headquarters when the truck rammed the wall. "It was just bad timing," he told the Associated Press. It was the deadliest single bombing attack on US forces in more than a year.