A car bomber blew himself up on Sunday at 5.20pm (1420 GMT) in the path of a US military convoy in the northern Iraqi city of Mosul, 370km north of Baghdad, police said.
Aljazeera reported that the attack occurred in al-Maliya neighbourhood, and that a tight security cordon had been thrown around the blast site by US soldiers.
The US military later said two US soldiers and two Iraqi soldiers were wounded in the attack.
Aljazeera has learned that hundreds of residents of al-Saqlawiya town, north of Falluja, took to the streets on Sunday to protest against the alleged detention of the mother of a wanted man who was subsequently killed during a raid by US forces on his house.
A delegation representing citizens of al-Saqlawiya headed towards a US military base to demand the release of the woman and others detained during the raid.
Elsewhere, unidentified armed men assassinated an official of the Supreme Council for Islamic Revolution in Iraq and two of his bodyguards near Baquba, 60km northeast of Baghdad, Aljazeera reported.
The incident happened when the assailants opened fire on the car carrying the three men to their homes near Abu Tamir village in the town of al-Khalis, north of Baquba, according to Aljazeera.
AFP quoted Iraqi police and Defence Ministry sources as saying that the killings took place at around 9am (0600 GMT) when anti-government fighters pulled up alongside in another car.
A boy looks at a crater created
by an explosion in Iraq's capital
Iraq military forces and police were also targets of the seemingly relentless anti-government attacks on Sunday.
Three Iraq soldiers were killed and three more were wounded in separate attacks in and around Baquba.
In the first instance, an ex-Iraq army lieutenant-colonel was shot dead by unknown assailants in his friend's shop, according to police.
Nearby, one soldier was killed and another was injured in an attack in Dhuluiyah, 70km north of Baghdad, police captain Umar Jumaha said.
Another soldier was killed and two more were wounded at around 11 am (0800 GMT) in violence in Balad, about 70km north of Baghdad, Asad Sudad, a police captain there, said.
Further north, four policemen were killed and six were wounded when rebels assaulted their police station in Tal Afar early on Sunday with mortars and small arms fire, Salah Muhammad, a doctor at the Tal Afar hospital, said.
One civilian was killed and six others wounded when fighting erupted later on Sunday in Tal Afar between anti-government fighters and the Iraqi army after one of their convoys was hit with a roadside bomb near the town's water pumping station, police and medical sources said.
The Mosul car bombing was just
one of Sunday's many attacks
A truck driver travelling in a US-guarded convoy was shot dead by anti-government fighters on the road to the northern city of Mosul, Police Lieutenant-Colonel Faris Mahdi said.
Police found a body in a field near Mahmudiya about 25km south of Baghdad, a local medical source said.
"The body was shot in the head and had been dead for three days," the source said on condition of anonymity.
Two Iraqi policemen were shot dead in Baghdad's western Yarmuk neighbourhood, a Defence Ministry official said.
Separately, four suspected anti-government fighters were arrested by the Iraqi army as they were driving south to the shrine city of Karbala from Latifiyah, an army officer told AFP.
The men had weapons in their car, he said.
Attacks on Iraqi security officers
show no signs of tapering off
Police are on high alert for the Shia festival of Arbain when pilgrims from around Iraq descend on Karbala to commemorate the death of Imam Husain, the grandson of Prophet Muhammad.
The holiday falls this Thursday.
At the Ministry of Science and Technology in al-Jadriya, south of Baghdad, one person was killed and five were wounded on Sunday when minister Rashid Umar Mandan's bodyguards fired warning shots to break up an impromptu demonstration of installation security guards, protesting against salary cuts, Aljazeera reported.
Police also said they found the decapitated body of an Iraq National Guard member on Saturday.
At least 1300 police and national guard personnel have been killed by anti-US and anti-government fighters since the fall of Saddam Hussein's government two years ago.