The four soldiers were killed and their Iraqi interpreter wounded when the bomb detonated near their vehicle during combat operations on Saturday, the military said.

An airman and three other soldiers were also reported dead on Saturday, taking US losses in this month alone to 68.

The airman died of wounds suffered when a roadside bomb exploded near his vehicle in the northern city of Tikrit.

A roadside bomb, followed by small arms fire, killed two US soldiers and wounded three in eastern Baghdad on Saturday while another soldier died the same day due to a "non-battle" cause, the military said.

The latest fatalities took the military's losses in Iraq to 3,545 since the March 2003 invasion, according to an AFP count based on Pentagon figures.

Earlier a group of armed men stormed a minibus and shot dead six men after dragging them out of the vehicle near the Iraqi Shia holy city of Karbala yesterday, a local official and a medic said.

The bus was ambushed in the town of Al-Shikat, west of Karbala, the official said on condition of anonymity, adding that a woman passenger in the bus was released before the men were gunned down.

"The men were dragged out of the bus, while the woman travelling with them was allowed to go. The six men were later shot dead," said the official, a member of the municipal council of the nearby town of Al-Thamur.

He said that one of the victims was fellow council member Karim Abdul Ridha.

A medic in the Karbala general hospital confirmed the attack.

In the northern town of Samarra, armed men attacked a police station and killed two policemen, injured another two policeman and five civilians, a local police officer and a medic said.

One gunman, allegedly an Arab foreign fighter, was killed in the clashes.

In southeastern Baghdad a civilian was killed and five others wounded in a roadside bomb blast, a medic said.

And former member of executed dictator Saddam Hussein's Baath party was shot dead in the southern city of Amarra, according to police.