At least four Iraqis were killed today when a civilian bus was caught in a blast west of Baghdad.
They said a bomb, possibly in a car, blew up on a main road in Khalidiyah village near the flashpoint of Falluja, west of Baghdad. US forces regularly use the road.
Earlier, at least seven Iraqi policemen were killed when a car bomb exploded north east of Baghdad , in an apparent attempt to assassinate the deputy governor of Diyala province.
US military spokesman Major Neal O'Brien said the bombing happened in Balad Ruz, 40 miles north east of the Iraqi capital.
Hospital officials in the area said at least 14 people were injured in the attack, including the deputy governor of Diyala province, Mr Aqil Hamid al-Adili.
Interim Iraqi Prime Minister Iyad Allawi
Police Brigadier Daoud Mahmoud said the car blew up outside Mr al-Adili's house in a residential area, killing several policemen assigned to protect him and wounding 16 people in all, some of them passers-by. Mr al-Adili was at home at the time.
The blast shattered the windows of Mr al-Adili's house, blew doors off their hinges and also slightly injured the deputy governor's nine-year-old son.
"This was a suicide attack with a booby-trapped car," he said. "We are busy moving casualties to the hospital."
Meanwhile, US marines backed by aircraft battled Shi'ite militia in the holy city of Najaf today, the fifth day of a bloody confrontation. Roughly 360 militants were killed in in the first four days, according to US military figures.
Witnesses said explosions rocked the city and machinegun fire echoed in the heart of Najaf, home to one of the most sacred sites for Shi'ite Muslims, as US aircraft flew overhead.
Smoke was seen rising from several locations near the city's ancient cemetery, the scene of close-quarter fighting in recent days.
Interim Prime Minister Iyad Allawi visited Najaf yesterday and demanded militiamen loyal to radical cleric Moqtada al-Sadr quit the holy sites.
"There is no negotiation with any militia that bears arms against Iraq and the Iraqi people," Mr Allawi told reporters in shell-scarred Najaf, 100 miles south of Baghdad. "I believe gunmen should leave the holy sites ... quickly, lay down their weapons and return to the rule of order and law."
The fighting in Najaf has spilled over to several areas of southern Iraq and Baghdad's mainly Shi'ite districts.