UK Foreign Secretary Jack Straw has said the United States must keep command of the joint military force in Iraq despite calls for a larger role for the United Nations.
Jack Straw: Britain and US want "vital role" for UN in Iraq
His comments echoed those of US Secretary of State Colin Powell, who is spearheading efforts to draft a new United Nations resolution that would encourage other countries to send more troops to Iraq.
Mr Powell met UN Secretary General Kofi Annan on Thursday to discuss security arrangements in the wake of Tuesday's devastating bomb attack on the UN headquarters in Baghdad.
Speaking at UN headquarters in New York, Mr Straw said the Americans had more troops in Iraq than any other country and "if you want there to be an effective military operation... the command has to be through the United States".
TROOPS IN IRAQ
US: More than 140,000
UK: About 11,000
Other nations: About 12,000
Iraqi police, border and security guards: 32,000
France, Germany, India and Pakistan are among nations who are unwilling to contribute troops to an operation being run by the occupying powers - the US and Britain.
Mr Powell also ruled out relinquishing US military control in Iraq, saying "ceding authority is not an issue we have had to discuss".
But referring to the exploratory talks at the UN, he said "perhaps additional language and a new resolution might encourage others".
Mr Powell stressed that the US-led force in Iraq was already multi-national, with 30 nations providing about 22,000 troops and more expected.
Divisions at UN
So far any discussion at the UN about giving the organisation a greater say in Iraq's political and economic future has faltered in the face of Washington's determination to keep overall military and political control in American hands, the BBC's Greg Barrow reports from New York.
Member states may now want to help the UN more in its hour of need. But diplomats say they are still unlikely to contribute troops as long as the United States, rather than the United Nations, maintains overall control, our correspondent says.
US forces in Iraq are facing constant hit-and-run attacks
France's deputy ambassador to the UN, Michel Duclos, said Washington would have to broaden the UN's political role in Iraq if it wanted other nations to contribute more.
"Sharing the burden and the responsibilities in a world of equal and sovereign nations means also sharing information and authority," he said.
Both Japan and Thailand are reported to be considering postponing or cancelling the deployment of the troops they had pledged in the wake of the bombing.
US Defence Secretary Donald Rumsfeld has said Washington has no plans to add to the more than 140,000 US troops already in Iraq.
The death toll from Tuesday's truck bomb on the UN's Baghdad headquarters is now at least 23.
The UN special representative for Iraq, Sergio Vieira de Mello, was among the dead.
Guards under scrutiny
A senior US official in Baghdad told The New York Times that investigators were examining the possibility that Iraqi security guards employed by the UN might have helped the bombers.
"We believe the UN's security was seriously compromised," the
the official was quoted as saying. "We have serious concerns about the placement of the vehicle [which carried the bomb]", he added.
US investigators at the scene of the blast said they had found human remains inside the truck used in the blast, heightening speculation it was a suicide bombing.
On Thursday, the Dubai-based al-Arabiya television station said it had received a statement from a previously unknown group, the Armed Vanguards of the Second Muhammad Army, claming responsibility for the attack.
After meeting Mr Powell, Mr Annan told UN staff in New York that the bomb attack in Iraq was the most deliberate and vicious against UN workers in the organisation's history.
UN staff are to resume normal operations in Iraq from Saturday.
The number of UN staff is being reduced in Iraq by about 100 and some administrative staff will be moving to bases in Jordan and Cyprus, a UN official said.
PLANNED MULTI-NATIONAL FORCE FOR IRAQ
Multi-national force: This will be the largest mission of its kind to take place without UN co-ordination or central Nato command
Cost: US reportedly expected to pay partner nations a total of more than $200m in airlift and support costs
Twenty-seven nations have sent troops:
Albania, Azerbaijan, Bulgaria, the Czech Republic, Denmark, the
Dominican Republic, El Salvador, Estonia, Georgia, Honduras,
Hungary, Italy, Kazakhstan, Latvia, Lithuania, Macedonia, Mongolia,
the Netherlands, Nicaragua, Norway, Poland, Romania, Slovakia, South
Korea, Spain, UK, Ukraine
Five nations' troops are expected:
Japan, Moldova, Philippines, Portugal and Thailand