Five US soldiers killed in Iraq

Seven others were wounded when a roadside bomb exploded as the patrol passed by.

The troops then came under sustained fire from small arms and rocket propelled grenades.

A US spokesman said the soldiers' unit continued what he called clearing operations in southern Baghdad, to try to reduce sectarian violence.

Ninety-nine US troops have been killed in Iraq so far in June. Last month, 126 American military personnel died, making May the deadliest month for US forces in Iraq since late 2004.

Changing tactics

The BBC's Baghdad correspondent Andrew North says that incidents like Thursday's, in which insurgents first use roadside bombs to attack US troops, then exploit the confusion afterwards to fire on them, have become more common.

Because so many insurgent bombs can now penetrate heavy armour, troops have been getting out of their vehicles more often, moving on foot in certain areas.

Our correspondent says this is a sign yet again of how the conflict here keeps changing, with insurgents often one step ahead.

Also on Friday, a bomb exploded under an oil pipeline south of Baghdad, spilling crude oil and sparking a huge fire, the Associated Press has reported, quoting Iraqi police sources.

The incident occurred in the town of Haswa, a town 50km (30 miles) south of the Iraqi capital.