An unidentified woman wearing an explosive belt has blown herself up at a police station in a mainly Sunni town in the province of Diyala, killing 15 people, AFP reports quoting an Iraqi interior ministry spokesman.

Reuters reported quoting Iraqi police that a suicide bomber killed 14 people outside a police recruitment centre on Tuesday.

They said 20 others had been wounded in the blast in the town of Muqdadiya, situated 90km northeast of the Iraqi capital.

Police said three among the wounded were civilians and added that the death toll may rise.

Baghad clashes

In central Baghdad, clashes erupted between US forces and fighters and an American helicopter came under ground fire but was not brought down, US and Iraqi officials said on Tuesday.

The fighting raged in Fadhil and Sheikh Omar, two Sunni-majority neighbourhoods, two Iraqi police officials said.

They spoke on condition of anonymity because they were not authorised to speak to the media.

Four civilians were injured in the clashes, police and a hospital official said, on the same condition of anonymity.

A US helicopter hovering over the battle "received some ground fire, but was not brought down", according to a senior US military official.

He spoke on condition of anonymity because US officials were still investigating the incident.

More US deaths

Three American soldiers have been killed and another has been wounded after a roadside bomb exploded near their patrol in Baghdad, the US military announced on Tuesday.

In a statement, the military said the incident took place in southeastern Baghdad.

The latest deaths bring to around 40 the number of US soldiers killed in Iraq this month, putting April on course to be one of the deadliest months for US soldiers in some time.

More than 3,280 American soldiers have been killed in Iraq since the 2003 invasion.

PHOTO CAPTION

US soldiers and Iraqi police commandos patrol a popular market in central Baghdad, 02 April 2007. (AFP)