The German diplomat has gone public with his criticisms of the sanction regime against Iraq.

On Friday, State Department spokesman James Rubin said the US did not believe Mr von Sponeck should be "leading this important effort".

Listing "his shortcomings in his current post", Mr Rubin said: "We think that [von Sponeck] has not been as forceful and as direct as he should be in confronting the Iraqi Government with the fact that enormous quantities of food and medicine remain in warehouses, undistributed".

On Tuesday UN Secretary-General Kofi Annan renewed Mr von Sponeck's term, despite opposition from London and Washington.

France has expressed support for the coordinator who was on his way to Baghdad on Friday.

The US has been criticised by hampering humanitarian aid to Iraq

Mr Rubin objected to the renewal of the official's term, saying that the US had lost confidence in Mr von Sponeck.

Mr Rubin said Mr von Sponeck had overstepped his mandate by "raising his own personal views as to the wisdom of the sanctions regime".

Mr von Sponeck told the UN at a briefing on the humanitarian situation in Iraq that decisions by the council's sanctions committee were a "deterrent for the implementation of the humanitarian programme."

Delays on imports

He said he had complained that the committee was blocking an increasing number of requests for imports to Iraq.

Mr Annan has himself criticised the US for delaying the delivery of some $700m worth of goods to Iraq under the 1996 oil-for-food programme. He said delivery of humanitarian aid to Iraq was, consequently, being hampered.

The latest attack against Mr von Sponeck came as the five permanent members of the Security Council met to discuss a deal to suspend sanctions in return for Baghdad allowing UN weapons inspectors into the country.

The meeting between the ambassadors of the US, Britain, France, Russia and China, is the first between the five powers on Iraqi police since their foreign ministers met on 23 September.

'Dance of the seven veils'

However Western diplomats said it would take several weeks before a resolution would be agreed.

One diplomat in the meeting described the process a "dance of the seven veils and this is just the first veil being lifted."

The UN Security Council has been at loggerheads over Iraqi policy since the US and UK launched air strikes on Iraq last December.

London and Washington take a hard line towards Baghdad, while Russia and China argue the sanctions are too harsh.

Iraq, however, has already dismissed efforts to suspend the sanctions as "unacceptable".

Iraqi opposition

On a visit to Geneva on Wednesday, Iraqi foreign minister Mohammed Saeed al-Sahaf said Iraq would only accept a complete lifting of sanctions, which were imposed after the 1990 invasion of Kuwait.

Also on Friday, the Iraqi authorities urged the UN to condemn the US for its support of Iraqi opposition groups.