US Defence Secretary Donald Rumsfeld has suggested that America would be prepared to take military action against Iraq - with or without Britain.
He told a press briefing that the US had alternative plans if the UK decides not to go to war with Iraq.
But Downing Street has expressed surprise at his remarks, insisting that if Saddam Hussein made the wrong moves, then Britain would be in at the front.
In fact, it was made clear that rather than scaling down the UK's involvement in the conflict, the opposite was happening.
In recent days military planners have been talking about Britain's "military contribution being greater than we thought".
But Mr Rumsfeld said: "To the extent that they are able to participate - in the event that the President decides to use force - that would obviously be welcomed.
"To the extent they are not, there are work arounds and they would not be involved, at least in that phase of it."
Asked if that meant the US would go to war without its "closest ally", he added: "That is an issue that the president will be addressing in the days ahead, one would assume."
The comments will come as a blow to Tony Blair who says he is willing to work "night and day" to secure enough common ground among UN security council members for a second resolution.
UN deadlock
He warned that Saddam Hussein will be "let off the hook" if France or Russia uses a veto over a further UN resolution.
UK diplomats at the UN have proposed a series of tests they say Baghdad should fulfil within a set time to prove that it is ready to hand over its weapons.
The proposals are part of an attempt to win wider support for a new UN resolution that gives the Iraqi leader a deadline to disarm before war.
Mr Blair hopes the plan will break the UN deadlock and ease mounting political pressure at home following an attack on his strategy by Clare Short, the international development secretary.
The prime minister's official spokesman insisted: "We want to ensure that the United Nations does not crumble into irrelevance."
Big test
But on Tuesday, six undecided UN members - Cameroon, Angola, Chile, Guinea, Mexico and Pakistan - suggested a 45-day deadline for Iraq to disarm.
This will be seen as a non-starter by America, which has rejected calls to extend the deadline beyond 17 March, insisting that a UN vote on war against Iraq will happen this week.
Former culture secretary Chris Smith criticised some opponents of war for suggesting the Iraq crisis could cost Mr Blair his job.
But he added: "I hope that even at this last stage he could have the courage and the statesmanship to say 'no, we are not going to go ahead with this', even if the Americans decide to do so."
Veteran Labour MP Tam Dalyell, a long-standing critic of Mr Blair's stance, forecast moves would be made to call a special party conference to challenge Mr Blair's authority.
But Labour Chairman John Reid told BBC Radio 4's Today programme that the prime minister enjoyed widespread support in his party and across the UK although he acknowledged Iraq was a "big test" for Mr Blair.
Deadline
On Monday, the prime minister telephoned Security Council members to discuss the benchmarks against which Iraqi compliance can be judged.
That paved the way for Britain's new proposals, which were drawn up and circulated by Britain's ambassador to the UN, Jeremy Greenstock.
On Tuesday, Mr Blair held talks in Downing Street with Portuguese Prime Minister Jose Manuel Durao Barroso who was supportive of his British counterpart's stance.
According to the Guardian newspaper, security sources at the UN suggest the new deadline could be pushed back "a few days" beyond the March 17 deadline in the draft resolution.
Downing Street seemed to indicate a degree of flexibility over the date.
France and Russia have warned that they would veto any new UN resolution, while UN Secretary General Kofi Annan has said the legitimacy of any military action without a new UN mandate would be "seriously impaired".
----------------------------------
Is this further proof of a US out of control? Will the US eventually lose even it's UK ally? And if so, will it go ahead with the invasion of Iraq as stated?
He told a press briefing that the US had alternative plans if the UK decides not to go to war with Iraq.
But Downing Street has expressed surprise at his remarks, insisting that if Saddam Hussein made the wrong moves, then Britain would be in at the front.
In fact, it was made clear that rather than scaling down the UK's involvement in the conflict, the opposite was happening.
In recent days military planners have been talking about Britain's "military contribution being greater than we thought".
But Mr Rumsfeld said: "To the extent that they are able to participate - in the event that the President decides to use force - that would obviously be welcomed.
"To the extent they are not, there are work arounds and they would not be involved, at least in that phase of it."
Asked if that meant the US would go to war without its "closest ally", he added: "That is an issue that the president will be addressing in the days ahead, one would assume."
The comments will come as a blow to Tony Blair who says he is willing to work "night and day" to secure enough common ground among UN security council members for a second resolution.
UN deadlock
He warned that Saddam Hussein will be "let off the hook" if France or Russia uses a veto over a further UN resolution.
UK diplomats at the UN have proposed a series of tests they say Baghdad should fulfil within a set time to prove that it is ready to hand over its weapons.
The proposals are part of an attempt to win wider support for a new UN resolution that gives the Iraqi leader a deadline to disarm before war.
Mr Blair hopes the plan will break the UN deadlock and ease mounting political pressure at home following an attack on his strategy by Clare Short, the international development secretary.
The prime minister's official spokesman insisted: "We want to ensure that the United Nations does not crumble into irrelevance."
Big test
But on Tuesday, six undecided UN members - Cameroon, Angola, Chile, Guinea, Mexico and Pakistan - suggested a 45-day deadline for Iraq to disarm.
This will be seen as a non-starter by America, which has rejected calls to extend the deadline beyond 17 March, insisting that a UN vote on war against Iraq will happen this week.
Former culture secretary Chris Smith criticised some opponents of war for suggesting the Iraq crisis could cost Mr Blair his job.
But he added: "I hope that even at this last stage he could have the courage and the statesmanship to say 'no, we are not going to go ahead with this', even if the Americans decide to do so."
Veteran Labour MP Tam Dalyell, a long-standing critic of Mr Blair's stance, forecast moves would be made to call a special party conference to challenge Mr Blair's authority.
But Labour Chairman John Reid told BBC Radio 4's Today programme that the prime minister enjoyed widespread support in his party and across the UK although he acknowledged Iraq was a "big test" for Mr Blair.
Deadline
On Monday, the prime minister telephoned Security Council members to discuss the benchmarks against which Iraqi compliance can be judged.
That paved the way for Britain's new proposals, which were drawn up and circulated by Britain's ambassador to the UN, Jeremy Greenstock.
On Tuesday, Mr Blair held talks in Downing Street with Portuguese Prime Minister Jose Manuel Durao Barroso who was supportive of his British counterpart's stance.
According to the Guardian newspaper, security sources at the UN suggest the new deadline could be pushed back "a few days" beyond the March 17 deadline in the draft resolution.
Downing Street seemed to indicate a degree of flexibility over the date.
France and Russia have warned that they would veto any new UN resolution, while UN Secretary General Kofi Annan has said the legitimacy of any military action without a new UN mandate would be "seriously impaired".
----------------------------------
Is this further proof of a US out of control? Will the US eventually lose even it's UK ally? And if so, will it go ahead with the invasion of Iraq as stated?
Comment