Colonel Musab al-Awadi, the director of Tribal Shaikhs Office in the interim Iraqi interior ministry, was shot dead in the Baya area in central Baghdad, reported Aljazeera's correspondent Atwar Bahjat on Monday. Two of his bodyguards were also killed.
The assassination was the latest violence to hit Iraq on Monday.
Earlier, two car bombs exploded simultaneously outside the main gates of a US occupation base in the northern Iraqi city of Mosul and a third car bomb was reported near a Baghdad bridge.
At least two people, including a child and her mother, were killed in the Mosul blasts.
One of the vehicles' drivers had approached the main gates of the US base, formerly the city's airport, and detonated the car bomb, reported Aljazeera's correspondent Abd Al-Qahhar Juma.
Another three US soldiers and three Iraqi guards were injured. The gates were heavily guarded by occupation troops and members of Iraq's national security forces, added Juma.
US troops closed all roads leading to the airport and prevented reporters from approaching the scene.
In Baghdad, at least three Iraqi civilians suffered injuries when a suspected car bomb exploded near the eastern entrance to the Sarafiya Bridge, according to witnesses at the scene.
A bomb placed in an Opel sedan detonated in the downtown area of the capital, said an Associated Press photographer at the scene.
Lieutenant Abbas Jasim said the driver had abandoned the car underneath the bridge spanning the Tigris river before it exploded.
There were no injuries in the
Also, Interior Ministry official Major Mushtaq Abbas said at least two mortars struck the former Higher Education Ministry near the central Saddun Street.
Abbas said the building had been under renovation and no casualties had been reported.
There were initial reports of mortars landing in at least two other nearby locations shortly after 8am (0400GMT).
Elsewhere, two Iraqi women working with British occupation troops in the southern city of Basra were killed in a drive by shooting, said police on Monday.
Assailants drove alongside the women's car as they were driving to work and sprayed gunfire at them, said Lieutenant Colonel Ali Kadhim. Another two women in the vehicle were injured, one seriously.
Armed men have routinely targeted Iraqis working for occupation forces, describing them as collaborators.
Late on Sunday, four resistance fighters were killed and two civilians injured during clashes with US occupation forces near Falluja on Sunday, reported Aljazeera's correspondent.
American troops detained three people.