Rumsfeld has been meeting other European defence ministers

Speaking after Nato talks in Brussels, Mr Rumsfeld said he was confident any separate EU military planning unit would not undermine the alliance.

But he refused to say if he thought the EU needed such a unit.

Meanwhile Nato Secretary General George Robertson urged Nato member countries to provide extra forces to boost the peacekeeping operation in Afghanistan.

Ministers also agreed to cut the Nato-led peacekeeping force in Bosnia from 12,000 to 7,000 by March.

Nato is expected to end the mission shortly afterwards and hand control to EU troops and police.

Diplomatic squirming

The issue of a special EU military planning unit has previously led to strong words and stormy talks.

But at a press conference following the Brussels meeting, Donald Rumsfeld said he was confident any EU defence plan would not threaten the US-led Nato alliance.

We must stay the course in Afghanistan - if we don't Afghanistan and its problems will appear on all of our doorsteps Lord Robertson

"I am confident and hopeful that things will sort through so that we end up with an arrangement that is not duplicative or competitive," he told reporters.

However, he refused to be drawn when asked if he thought the European Union needed its own military planning capability.

Mr Rumsfeld was quoted as saying, upon arrival in Brussels on Sunday: "I think there is no reason for something else to be competitive with Nato."

Lord Robertson also avoided straight answers on the issue by maintaining he did not know the details of the EU's plans, but he insisted that they must avoid unnecessary duplication of effort with Nato.

The BBC's Angus Roxburgh says the diplomatic squirming suggests considerable unease in the alliance.

What appears to worry the Americans most is that the EU's defence plans are evolving rapidly and could yet turn into something more independent, says our correspondent.

Afghanistan

At the Nato meeting, Lord Robertson asked for 14 helicopters and around 400 special troops to add to the current force of 5,700 in the Afghan capital Kabul.

He also wants extra forces to enable the alliance to expand its operations outwards to cover up to 17 provincial cities.

The EU military planning unit is smaller than originally suggested

"Governments must have the political will to deploy and to use [their] forces in much larger numbers than at present," he said.

"We must stay the course in Afghanistan... If we don't Afghanistan and its problems will appear on all of our doorsteps."

Correspondents say that so far some nations have proved reluctant to provide aircraft, although Norway, Iceland, Spain and others have offered some of the personnel needed.

Military planning unit

The EU plans agreed at the weekend include a smaller-scale European military planning unit than the new headquarters originally proposed by France and Germany at the height of the trans-Atlantic Iraq war dispute.

The small planning unit will operate in parallel with a European cell at Shape, Nato's military HQ outside Brussels.

The revised plan was enough of a compromise to win the support of the UK, which had tried to placate EU allies without estranging the US.

Foreign Secretary Jack Straw said the plans, not yet formally approved by the whole EU, would still leave Nato in the driving seat of Europe's defence.