Analysts say al-Qaeda is trying to destabilise Iraq ahead of March polls
A series of car bombs has exploded in two Iraqi cities killing at least eight people, police say.
In central Baghdad three bombs killed at least four people and wounded 14 outside the heavily fortified Green Zone.
That attack was followed by another co-ordinated car bombing in the northern city of Mosul where four people were killed and 40 injured.
Analysts say al-Qaeda is trying to destabilise Iraq ahead of March polls.
The blasts in Baghdad occurred near the Iranian embassy, the foreign ministry and the immigration ministry, reports say.
In Mosul two Syrian Orthodox Christian churches and a church school were attacked.
Analysts say al-Qaeda is trying to destabilise Iraq before elections
The blasts come a week after at least 127 people were killed in multiple car bombings in Baghdad.
The latest attacks struck days after Prime Minister Nouri al-Maliki blamed opposition rivalry for security lapses.
The blasts in Baghdad happened within minutes of each other shortly after 0730 local time (0430 GMT).
"Dear God, how on earth do the police and soldiers let these booby-trapped vehicles through," Um Ali told AFP news agency.
Her son Maki, 28, had been seriously wounded in the blast, she said.
"A man left his car this morning and headed off almost at a run. When my son approached the vehicle, it blew up," she said.
Police officials told reporters they had found and defused a fourth bomb in a pick-up truck nearby.
Hours after the Baghdad blasts, twin car bombs were detonated near churches in Mosul.
As emergency services and rescuers gathered at the site of the first bomb, a second went off.
Some of the wounded were school children, police and medics told reporters.
"We were in class and the lesson was about to start when there was a huge blast and the windows shattered. I was wounded in the arm," 15-year-old student Karim Jassem, told AFP.
Another bomb went off at a church in a different part of town, but no-one was injured.
Mosul remains a stronghold of Sunni Islamist militants, and Christians have often been targets of violence since the invasion in 2003.
DEADLY ATTACKS SINCE 2003
Mar 2004: 171 killed in bombings in Baghdad and Karbala
Nov 2006: 202 killed in multiple blasts in Baghdad
Mar 2007: 152 killed in truck bombing in Talafar
Apr 2007: 191 killed in car bombings in Baghdad
Aug 2007: More than 500 killed in attacks on villages near Sinjar
Aug 2009: 95 killed in lorry bombs in Baghdad
Oct 2009: 155 killed in twin truck bomb attacks in Baghdad
Dec 2009: At least 127 killed in a series of car bombs in Baghdad
Source: News agencies, BBC
Iraqi government figures have shown that violence generally has fallen over the past 18 months.
But in early December at least 127 people were reported killed in five connected suicide car bombs targeting government-run buildings.
In October co-ordinated bomb attacks killed at least 155 people and wounded hundreds in Baghdad.
Correspondents say that besides occasional massive bombings, insurgents also stage frequent smaller-scale attacks against targets such as marketplaces, mosques or schools.
Security has been heightened ahead of March's parliamentary elections, after which the US has been planning to withdraw forces.