In a double car bomb attack at the Iraqi Interior Ministry complex in Baghdad's central al-Jadiriyah neighbourhood, at least 14 people were killed and 40 wounded, an Iraqi police captain told Aljazeera.
And in a third attack in al-Mahawil - near the town of al-Hilla -at least four policeman died and six more were wounded when a bomb was hurled at security officials guarding the local municipal headquarters.
The Baghdad bombers blew up their cars on Thursday morning near a fortified section of the ministry, police said.
The bombs detonated in quick succession about 200 metres apart on a busy street packed with traffic. A Reuters cameraman said children were among the dead.
Other witnesses said 15 cars were destroyed in the explosions and human debris was scattered over a wide area.
The blasts occurred near Iraqi police vehicles protecting an entrance to the ministry complex.
Iraqi journalist Walid Khalid told Aljazeera that as the convoy was about to enter the complex, the two bombers attacked from the back and the front.
A surge in violence is erasing the
gains made since the election
He said the toll might rise because of the critical injuries among civilians and police officers.
Accounts of the casualties differed.
An Interior Ministry official, who asked not to be named, said at least 15 people had been killed.
Another ministry official, Captain Ahmad Ismail, said 18 were killed and 36 wounded.
Khalid said US helicopters were seen flying above the attack site, where other Iraqi government offices are located.
An Iraqi police captain told Aljazeera many of the victims were part of the highway patrol responsible for accompanying oil trucks from al-Dura refinery to the refinery at Baiji.
He said police had found a vehicle with an unexploded bomb near the scene of the blasts and were working on dismantling the explosive.
A police officer said he thought the convoy he was travelling in was targeted.
"We were cutting through the traffic jam when a car in the middle of the crowded street blew up. We crossed over to the other side to avoid the traffic jam and another car tried to cross ... but flipped over and when it did it also blew up," Abbas Jhudier said.
At least 15 cars were destroyed
in the double car-bomb attack
"The first car was in the middle of the traffic jam and caused a lot of casualties."
An official at nearby Yarmuk hospital said about 20 people had been brought in with injuries. Several other wounded people were taken to another hospital.
The blasts took place at about 10am (0600 GMT) and sent a plume of black smoke over the Iraqi capital.
Iraq's al-Qaida wing, Qaidat al-Jihad fi bilad al-rafidayn (The Jihad's Base in the Land of Two Rivers), has claimed responsibility for the twin bombs according to a statement posted on the internet.
"Two lions from the martyrs' brigade ... launched themselves - one attacked an apostate police patrol guarding the office of the apostate minister while the second hit the rear end of a 9-car patrol," the group led by Jordanian Abu Musab al-Zarqawi said in a statement posted on a website.
Aljazeera quoted Iraqi police sources as saying on Thursday morning unidentified fighters assassinated one of the new officers at the Iraqi intelligence service in al-Mansur neighbourhood, west of Baghdad.
Attackers shot and killed 1st Lieutenant Firas Hussain near his house as he was going to work at Iraq's intelligence service, police Major Musa Abd al-Karim said.
"Two lions from the martyrs' brigade ... launched themselves - one attacked an apostate police patrol guarding the office of the apostate minister while the second hit the rear end of a 9-car patrol"
The Jihad's Base in the Land of Two Rivers statement
There was more violence outside Baghdad on Thursday. In Latifiya, south of the capital, armed men shot and killed the mayor.
Armed men attacked police patrolling near the central Iraq city of Baquba, killing one officer and wounding three others, Lieutenant-Colonel Muthafar al-Juburi said.
In the northern oil city of Kirkuk, three Iraqi police officers were killed and four people wounded when armed men attacked a new police station, police said.
The attack happened at about 8am (0400 GMT) when police were preparing to go for a patrol in the southern neighbourhood of Adala, said police Colonel Munis Ishak.
Twelve oil facility guards were
killed in Kirkuk on Wednesday
The police station had opened seven days ago, he said, adding that one of the wounded was a civilian.
Twelve members of a special Iraqi oil facilities protection force were killed in a bomb attack north of Kirkuk on Wednesday.
In addition to strikes against security forces, the Kirkuk region is the scene of frequent attacks against vital oil facilities and violence among its three main ethnic communities: Sunni Arabs, Kurds and Turkmen.
Also on Thursday morning, a car bomb exploded near a US military post in the northern city of Tikrit, Aljazeera learned. Officials in Salah al-Din governorate said a building used by US forces was targeted.
Police said four Iraqis were killed and nine wounded.