A Shiite radical MP was assassinated in a bomb attack on Thursday in Baghdad's Shiite stronghold of Sadr City, marking the first killing of a lawmaker in 18 months, his Sadrist faction said.

"The political committee announces the death of Saleh al-Ogayly (MP) resulting from injuries sustained in a bomb attack in Baghdad today," a statement said.

At least one bystander was also killed in the attack that was carried out by planting a home-made bomb on a parked motorcycle, security officials said, adding that four people were also wounded.

Security officials confirmed that the bomb had targeted Ogayly (41), a member of the parliamentary group of radical anti-US cleric Moqtada al-Sadr.

He becomes the first Iraqi MP to be killed since the 12 April 2007 suicide bombing of the national parliament, where one legislator and seven others died.

Security officials said a second roadside bombing in Baghdad on Thursday killed a civilian and wounded four people, two of them policemen. Both attacks were in Sadr City, the impoverished northeastern Baghdad district where two million people live.

A driver of a car was killed in central Baghdad on Thursday when a bomb went off inside his vehicle, police said.

Heavy fighting in Sadr City in March and April between Sadr's Mahdi Army militia and security forces left hundreds dead before a ceasefire went into effect in May.

Despite the truce, the district has seen frequent violence.

In another roadside bomb attack just north of Baghdad, an Iraqi Sunni militia leader working with US forces was killed along with two of his children and a nephew, security officials said.

Abbas Khudair, who heads a Sahwa, or Awakening group, that is paid by American forces, was targeted as he drove with his family in the Al-Uthaim area in Baquba, the capital of Diyala province, officials said.

An AFP photographer said the bodies of Khudair, his son and daughter and the nephew were taken to the local hospital, where five more relatives were being treated for blast wounds.

Sahwa members are mostly former insurgents who fought US and Iraqi forces after dictator Saddam Hussein's fall in 2003, but helped curb violence since late 2006 after they sided with the Americans to battle al-Qaeda.

The latest attacks came a day after a woman suicide bomber killed nine people outside a court house in Baquba, 60 kilometres north of the capital.

Meanwhile, in the northern oil city of Kirkuk, another Sahwa leader was shot dead on Wednesday night by unidentified gunmen, police Captain Firas al-Juburi said.

Al-Qaeda has been blamed by the US military for most of the brutal violence in Iraq since the fall of Saddam Hussein's regime.

AFP