Speaking as seven ex-communist countries were accorded a ceremonial welcome to the North Atlantic Treaty Organisation, Powell reiterated Washington's belief that NATO as a whole should take a formal role in the shattered nation.

Eighteen of the newly enlarged alliance's 26 members have already contributed troops to the occupation force, including six of the seven new entrants.

But NATO countries such as France and Germany, which opposed the US-led war, have stressed that another resolution at the United Nations Security Council will be needed before they can consider joining a NATO mission in Iraq.

"The US believes the alliance should consider a new collective role after the return of sovereignty to an Iraqi government (planned for July 1)," Powell told a news conference.

"As we get closer to the date for the transfer of sovereignty, we will have to see at that point what coordination, what consultations, will be appropriate with the new government," he said.

"But I would think it unlikely that NATO would undertake a formal, collective alliance role before full sovereignty... has been returned.

"I'm also relatively confident that that government would welcome that kind of assistance from the international community," Powell added.

He said NATO could take over a sector in Iraq or train Iraqi security forces, but was unlikely to assume command of the whole country from US top brass.

NATO Secretary-General Jaap de Hoop Scheffer said he saw "a great deal of support" for the alliance to deploy in Iraq -- but only at the request of the UN and a sovereign Iraqi government.

Cracks in the international coalition in Iraq have appeared with Spain's new Socialist government vowing to pull its troops out unless the Security Council blesses the force with a UN mandate.

But some of the ex-communist countries newly enrolled in NATO vowed to keep their troops in Iraq, while calling for greater international involvement to restore stability to a nation rocked by near-daily outbreaks of violence.

Romanian Foreign Minister Mircea Geoana said it was high time for transatlantic divisions over the war in Iraq, which last year plunged NATO into its worst-ever crisis, to be put aside.

"We have a fundamental interest... to have Iraq become as soon as possible a self-governing, democratic, more prosperous and gradually more stable nation," he said.

"All of us, the countries that have suffered under communist dictatorship, have not only a strategic necessity to stabilise Iraq for the sake of the broader region, but also a moral obligation to assist this nation," he added.

Bulgarian Foreign Minister Solomon Passi backed the Romanian stance.

"Indeed we are for much stronger international support in Iraq -- we would support a much stronger NATO commitment in Iraq, we would support a much stronger UN commitment in Iraq," he said.

Slovak Foreign Minister Eduard Kukan, asked whether his own country would stay the course in Iraq, replied emphatically: "Yes, sir."

Geoana noted that Romania would chair the UN Security Council in July, when any new resolutions are expected to be submitted by the United States and its allies.

"The next few weeks and months will be decisive to the way in which we can return power to Iraqi authorities," he said, adding that a UN mandate will be "politically and legally needed to assure this transfer".

WAR.WIRE