"An improvised explosive device exploded against a two-vehicle convoy in Baghdad today," a spokeswoman from the US military said on Saturday.

"The explosion resulted in the death of one soldier and the injury of two others," she said.

A US military statement later said the attack took place in the al-Azamiyah district of Baghdad at around 05:30 GMT. 

Witnesses had reported an explosion on an overpass in the Tunis neighborhood, within the al-Azamiyah district, which they said had left several US casualties and a Humvee damaged at around the same time.

A loud explosion was heard in the Iraqi capital at around 02:00 GMT, but the cause was still not clear, according to the
US military. 

The soldier's death has raised to 161 the number of US troops killed in combat in Iraq since 1 May, when US President George Bush declared major hostilities over.