A Polish-led force has taken over a part of central Iraq from US Marines as Washington seeks to relieve the burden on its troops by widening international participation in Iraq's security.
The Marines, in charge of the area for several months, handed over control of a south-central zone of Iraq to the Polish-led multinational force.
"I have absolute faith and confidence in the 21 nations that will assume their responsibilities today," Lieutenant-General Ricardo Sanchez, commander of US troops in Iraq, told a ceremony on Wednesday in an open air amphitheatre in ancient Babylon.
With security deteriorating in the occupied country and US soldiers dying nearly every day, President George W. Bush took steps to bring in the United Nations to share the burden of stabilising and running Iraq.
In Baghdad, 25 ministers were sworn in and were set to get down to work in what the US-led administration says is another step towards handing the reins of power back to Iraqis.
A senior US official last night said that Bush had directed Secretary of State Colin Powell to open negotiations at the UN Security Council on a resolution aimed at building a wider multinational force and getting UN help to build political stability.
"We've got language (of a draft UN resolution). It enhances, it elaborates, it talks about how countries can contribute," a State Department official said.
"It's on how to define further the vital role of the UN in political, military and economic areas and how to provide ways for the UN members to support efforts by the Iraqi people."
UN envoys said the draft might include a role for the United Nations in helping to prepare elections in Iraq.