Aid has begun to flow to a small northern Shiite town in Iraq, a day after security forces backed by Iran-allied Shiite militias and US airstrikes broke a two-month siege by Sunni militants.

The UN joined the row over Iraqis killed by private American security firms today and war said individuals could face war crimes charges.

Sectarian violence continued to claim the lives of a large number of Iraqi civilians in Sunni Arab and Shiite neighbourhoods of Iraq’s capital, despite the coalition’s new Baghdad security plan, the UN said today.

Iraq has reported that about 12,000 civilians were killed last year – the third full year since the US-led invasion – with a dramatic rise in the last three months, when 5,000 died.