The United States is sticking to its demand for the removal of Iraqi President Saddam Hussein's regime, despite Baghdad's offer to re-engage with a United Nations weapons inspection programme.

What he (Saddam) should say is: 'Yes, I accept any time, anywhere, any place unfettered inspections'

Sean McCormack US National Security Council

"Our policy remains the same... and that is regime change," said US National Security Council spokesman Sean McCormack. "Everyone understands the nature of Saddam Hussein and his regime".

He said any discussion on renewed inspections should be "very short".

"What he (Saddam) should say is: 'Yes, I accept any time, anywhere, any place unfettered inspections'."

For his part, UN Secretary General Kofi Annan gave a cautious welcome to Iraq's invitation for the head of the weapons inspection team to visit Baghdad.

However, a spokesman for Mr Annan warned that the procedure proposed by the Iraqis was "at variance" with the methods agreed by the UN Security Council.

No decision will be taken on a response to the invitation until a council meeting next week.

Speculation has been growing about an attack on Iraq by the US, which alleges that Saddam Hussein is developing weapons of mass destruction.

The BBC's Jon Leyne in Washington says the US administration has been careful to play down the significance of an Iraqi offer it views with deep scepticism, and President George W Bush has left the capital for the weekend without commenting on it.

Other members of the UN Security Council appear to be divided over the offer - Russia and France welcomed it but Britain is sceptical.

The letter from the Iraqi Foreign Minister, Naji Sabri, was sent to Mr Annan on Thursday inviting the chief inspector, Hans Blix, for what was called "technical talks".

Skilled negotiators

The BBC's Greg Barrow, at the United Nations, says the last thing UN officials want to do is to rush into making a response - they know that the Iraqis are skilled negotiators.

Iraq is suspected of rebuilding its weapons programme

The UN will want to know exactly where such discussions are going to lead.

Our correspondent says that, despite their obvious caution, officials still want to believe that the Iraqis are moving towards a return of inspectors after an absence of more than four years.

Iqbal Riza, Chief of Staff in Mr Annan's office said: "(It is) certainly a positive development to receive any sort of proposal from Iraq in this situation."

He said the substance of the letter would have to be evaluated by Mr Annan and Doctor Hans Blix, the head of the UN monitoring and verification commission (Unmovic).

Arms inspection timeline

Feb 1991: Gulf War ends - Iraq subjected to UN sanctions and arms inspections Jan 1998: Iraq blocks mission, accuses inspectors of spying for US Feb 1998: Kofi Annan reaches deal with Baghdad Oct 1998: Iraq ceases co-operation with Unscom Nov 1998: Inspectors return to Iraq Dec 1998: UN pulls out inspectors - US air strikes begin Dec 1999: Unscom replaced by Unmovic Jul 2002: UN-Iraq talks end without deal Aug 2002: Iraq invites Unmovic chief to Baghdad

UN inspectors left Iraq in 1998, complaining of a lack of co-operation from the Iraqi Government.

News of the Iraqi invitation caused global oil prices to fall on Friday, as traders saw the move as reducing the chances of military conflict in the Middle East.

Verification of Iraqi weapons programmes is a key condition for the lifting of UN sanctions imposed after Iraq invaded Kuwait in 1990.

The letter came on the eve of the 12th anniversary of the Iraqi invasion.

The UK Foreign Office said that Saddam Hussein had what it called a long history of playing games.

In contrast, the Russian Foreign Ministry said in a statement: "Moscow considers the Iraqi proposal as an important step in the right direction towards resolving the crisis through political and diplomatic means in the framework of UN Security Council resolutions."

France said it supported "all efforts that might lead to Iraq respecting its obligations towards the United Nations Security Council".