The latest attacks against the long-oppressed Shia majority were carried out as politicians remained locked in efforts to break a deadlock over the formation of a new government two months after Iraq's watershed election.

And amid the violence, more of Iraq's children were going hungry, with figures for malnutrition among the very young having doubled since the 2003 US-led invasion, according to a report to a UN commission.

In the latest attack on Thursday, seven people were killed by a car bomb in the centre of the restive northern city of Samarra. It exploded as a US-Iraqi patrol drove past the golden-domed shrine where two of the 12 Shia Imams Ali al-Hadi and Hassan al-Askari are believed to be buried. Four of the dead were civilians.

In a reminder of the perils for foreigners, Arabic satellite channel Al-Jazeera broadcast a video showing a US citizen and three Romanian journalists taken hostage last Monday by an unidentified group in Iraq.

Two masked men were seen pointing their weapons at the four visibly frightened hostages huddled on the ground.