Another suicide bomber detonated his explosives-laden car at an Iraqi army checkpoint in the Al-Tahreer neighbourhood and killed three civilians, Major General Khalid Abdul Sattar, spokesman for Nineveh's security plan, said.
A third suicide bomber detonated an explosives-packed fuel tanker in the city's western Tal al-Ruman area and wounded 15 civilians, he said.
The fourth attack was a parked car bomb which exploded in the southern Al-Tayran area and wounded five people, Sattar added.
The US military claims Mosul, Iraq's third largest city, is the last urban bastion of the armed group al-Qaeda in Iraq.
Sadr City fighting
Fighters loyal to al-Sadr have clashed daily with US-backed Iraqi security forces since Nuri al-Maliki, Iraq's prime minister, launched a crackdown against Shia militias a month ago.
Iraqi security sources said that eight people, including a child and a woman, were killed and 27 others were wounded in clashes on Friday and Saturday between Mahdi Army militia and US forces in al-Sadr City in eastern Baghdad.
They said that US aeroplanes had bombed positions in the district.
Last week, al-Sadr issued what he called a "final warning" to the Shia-led government to halt its offensive against his supporters or face an "open war until liberation".
|US aircraft were reported to have bombed|
locations in Sadr City [AFP]
However, on Friday the Shia leader clarified that his threat applied only to American forces and called for an end to Iraqi bloodshed.
Police said five bodies were found in different districts in Baghdad on Saturday.
In the west of the capital, Iraqi police said that two leaders of the so-called Awakening council of al-Amiriya district were killed when a suicide bomber rammed an explosives-laden car into a building where the US-finance Sunni fighters were meeting.
Eight people, including Abu al-Abed, commander of the Awakening council of al-Amiriya, were injured.
US forces, meanwhile, reported killing two suspected fighters and arresting five others in Iraq's Salahuddin province.
Eight policemen were also injured in sporadic attacks throughout the province.
Separately, an Iraqi soldier was killed and two civilians were wounded in the eastern city of Kut when joint US and Iraqi forces raided posts of militias and arrested 25 suspects.