Eight police commandos were also wounded when a car bomb exploded on Wednesday near a school in the southern Baghdad district of Dura, an Interior Ministry official said.
An Iraqi civilian was killed and seven others wounded in another car bomb attack near a US convoy in Saidiyah, also in the south of the capital, an Interior Ministry source said, adding that witnesses reported US casualties.
"I can confirm there was a car bomb attack in southern Baghdad around 5:00 pm (1300 GMT) but we have no reports of casualties nor if a US patrol was targeted," US military spokesman Lieutenant Jamie Davis told reporters.
Police chief killed
In the restive northern commercial hub of Mosul, a police chief from the nearby town of Shorgat was shot dead by armed men. "Colonel Muklef Mussa, who was in Mosul for a law school night course was killed at 12:45pm (0845 GMT) by armed men who escaped," said Mohammed Fathi, commander of the local police force.
About 600 people have been
killed in a surge of violence
Another Iraqi police officer was killed by a bomb in Dohuk farther north, police said. One bomb went off and when an Iraqi police patrol arrived, another one exploded, killing the officer.
In addition, an Iraqi soldier and a fighter were killed in an exchange of gunfire close to Balad about 70 kilometres north of the capital, police said.
Many of those killed in this month's violence have been members of Iraqi security forces struggling to bring the country's increasing lawlessness under control.
Meanwhile, hundreds of demonstrators took to the streets of the holy Shia city of Najaf on Wednesday to demand that a Sunni religious leader be taken to task for accusing a former Shia militia of killing 14 Sunnis.
Leading Sunni cleric Hareth al-Dhari last week charged that the Shia Badr Organisation had killed 14 Sunnis, including three clerics, ratcheting up sectarian tensions between the newly empowered Shia and disenfranchised Sunni communities.
"We condemn Dhari's declarations and we demand he be judged," said a banner held by demonstrators loyal to the Supreme Council for Islamic Revolution in Iraq (Sciri), a leading political party in the winning Shia bloc of Iraq's new government.
The Badr Organisation is the former armed wing of Sciri. Members of the group, which has worked closely with the new Interior Ministry in recent weeks, say they have disarmed.
Shia leaders have denied Dhari's allegations and government leaders have threatened legal action against him. Dhari "could have supported national unity instead of fanning the flames of sectarian tension," said a Najaf marcher.
Sadr (L) has offered to mediate
between Shias and Sunnis
Sheikh Khaled Numani, vice president of the Najaf provincial council and a Sciri leader, said the demonstration represents Iraqis' will to "prevent division among themselves".
Reclusive Shia cleric Moqtada Sadr -who fought US forces in two major battles last year- has resurfaced in recent days, offering to mediate between Shia and Sunnis to lower tensions.