A blast in a bus travelling in Baghdad's Sadr City killed five people and wounded eight on Thursday, police said.
The sprawling slum is a stronghold of Muqtada al-Sadr, the Shia cleric who has reached across Iraq's sectarian divide and called for Sunni and Shia solidarity in fighting US occupation.
"A car loaded with explosives was parked not far from a market in Sadr City," an official said.
In another attack in Baghdad, four people were killed and 11
wounded, mostly women, when a bomb exploded in a market in the mixed southeastern Jaafaraniya district, an interior ministry official said.
Police evacuated the market after finding a second bomb, which they were working to disarm.
A police commando was killed and two wounded in the western
Jihad district when a roadside bomb exploded next to their patrol, the official added.
The bodyguard of a Sunni political leader, Adnan al-Dulaimi,
died and five others were wounded when their cars came under fire in the west of the capital. Dulaimi was not present during the attack.
In Khales, north of Baghdad, two Iraqis were killed and one was wounded on Thursday in a roadside bomb blast.
Eleven people were wounded in
the Jaafaraniya attack
In Baquba, to the northeast, two more people died, including a policeman, and six were wounded in a series of attacksIn the northern Iraqi city of Tikrit, a police officer said gunmen killed seven Iraqi soldiers and four policemen at a checkpoint early on Thursday.
The officer said that "the attack occurred at around 1.30am (2230 GMT on Wednesday) when gunmen, travelling in four cars, attacked the checkpoint near al-Dawr", 150km north of Baghdad.
Police cars burnt
The attackers also burnt some police cars at the checkpoint, the officer said.
In Mosul, four policemen were gunned down as they drove away from a police academy in the centre of the city.
In southern Iraq, a Sunni cleric was killed near the port city
Hundreds of Iraqis have died since the bombing of the the al-Askari shrine, an important Shia religious site in Samarra, on 22 February.
The bombing set in motion a series of sectarian reprisal attacks that threaten to push Iraq into civil war.