Violence has flared once again across Iraq's Sunni Muslim heartland.
The suicide car bomb exploded near a market place in Baiji
In the worst incident, in the town of Baiji north of the capital Baghdad, a suicide bomb targeting a US military convoy killed 14 Iraqis.
In the city of Ramadi, to the west of Baghdad, clashes erupted between insurgents and US troops.
And US bombardments of the city of Falluja, where the Americans say their mission to flush out insurgents is almost complete, have continued.
The US says it is targeting the city's final remaining pockets of resistance.
Baiji, the site of the country's largest oil refinery and a major power station, saw a suicide car bomber ram his vehicle into a US military convoy, causing a huge explosion.
The attack took place near a market close to the centre of the town, which lies some 250km (155 miles) north of Baghdad.
An estimated 22 Iraqis were wounded in the incident and a US military spokesman said three soldiers were also hurt.
In Ramadi, to the west of the former rebel stronghold of Falluja, nine Iraqis died as US forces confronted large groups of gunmen firing rockets and mortars.
Meanwhile, efforts to suppress the last remnants of the Iraqi insurgency continue in Falluja.
Mortar fire and heavy explosive rounds targeted areas in the city where the US believes insurgents are still hiding.
Iraq's interim government says some 1,600 rebels lie dead in the rubble of the city, and civilians have been trying to collect their dead between upsurges in the fighting.
The Associated Press news agency reports that some insurgents have sneaked back into the city by swimming across the Euphrates River.
According to AP, the US military says the city of Mosul appears calmer after a struggle to restore control there.
In other developments:
Iraq's interior ministry says it is investigating reports that a group of police recruits were kidnapped as they returned from training in Jordan
Iraqis have expressed their revulsion at the murder of Dublin-born aid worker, Margaret Hassan, believed to have been shot dead by her captors
Interim Prime Minister Iyad Allawi says he is "very concerned" about the alleged killing of an unarmed Iraqi prisoner by a US marine in Falluja
The Nato military alliance says it will set up a training centre for Iraqi security forces near Baghdad which will train 1,000 Iraqi recruits a year.