One US soldier was killed and 18 more wounded when a suicide car bomb exploded near to a patrol base in northern Iraq today.

Two Iraqi contractors were also injured in the blast, which the US military blamed on al-Qaeda in Iraq.

It is rare for such a high number of US troops to be injured in a single attack.

The bombing took place just after 2pm, south west of the oil-rich city of Kirkuk.

Another US soldier died when his vehicle was hit by a roadside bomb as it travelled through eastern Baghdad yesterday.

The deaths brought to 4,093 the number of American soldiers killed since the March 2003 invasion.

In other violence, three people were killed and seven wounded in a mortar attack on the fortified Green Zone in Baghdad, home to the Iraqi Government as well as the British and US embassies.

Rockets fired by Shia militiamen rained down on the Green Zone in late March and early April during offensives in Sadr City. Such attacks have dropped recently as Iraqi forces span out across the Baghdad Shia slum, from where they were launched.

Also in Baghdad today, four police recruits were killed in an attack on the National Police headquarters, authorities said. Another 22 people were wounded near the building's gate where recruits were gathering, they said. Police gave conflicting reports about whether the attackers used mortars or a roadside bomb.

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