By Paul Reynolds BBC News Online world affairs correspondent

US and British diplomatic hopes of setting quick and tough new rules on Iraqi disarmament and inspections have been dashed.

They have been knocked off course by opposition from other members of the United Nations Security Council and by a deft Iraqi decision to promise cooperation on the basis of the old rules.

Powell: No going back "into the swamp"

Now there is a very real prospect that the US - probably supported by the UK - will march off to war, leaving the UN and others behind.

That moment has not quite arrived, but the question is, has it simply been delayed?

It has been clear for a long time that if the US does not get Iraq to disarm through diplomacy, it will get Iraq to disarm through war.

And of course, if the real US intention is to remove Saddam Hussein, it will not mind if diplomacy fails.

'Strong views'

For the moment, however, the diplomacy continues.

And it was given a boost when the Russian Foreign Minister Igor Ivanov said that, after all, a new resolution might be needed to make the work of the inspectors "effective."

Saddam's palaces have proved central to diplomacy over inspections

US Secretary of State Colin Powell said that he would go on seeking a resolution over the "next couple of weeks".

He still wants one resolution, with conditions, a warning and a threat of force wrapped up into one.

He admitted that there had been "strong views" coming back from Russia, China and France.

France, for example, wants the process split in two, with a warning first and only later - and only if really necessary - an authorisation of force.

'Red rag' to Iraq

The new US and UK proposal is so tough that some observers feel that Iraq is bound to contravene it, which in turn would lay it open to the use of "all necessary means", the phrase used by the Council in 1990 to authorize the Gulf War.

Under the new proposals, there would be have to be an Iraqi declaration about its weapons programmes upfront, no exceptions from surprise inspections and a whole range of new measures, including no-fly and no-drive zones around inspection sites.

The new proposals also call for the right of any Security Council member to demand any inspection and place its own people on the inspection teams.

That alone is a red rag to Iraq, since last time it was found that US agents had been mingling with the inspectors.

Any failure by Iraq to comply with any one of the conditions would be considered enough for an attack.

Road to war?

In the meantime, the US opposes the return of the inspectors who agreed with Iraqi negotiators in Vienna on Tuesday that the much less stringent conditions and timetable set down by the council in resolution 1284 in December 1999 should apply.

That resolution allows for the presidential sites to be the subject of special measures, giving Iraq notice of inspections.

Mr Powell said that Hans Blix, the head of the inspections commission Unmovic, was a servant of the UN and would "carry out what the Security Council instructs him to do".

One US official said that Washington would "thwart" the return of the inspectors on the old terms.

And Mr Powell said there would be no going back "into the swamp".

In the world of big power diplomacy, it is unlikely that the UN Secretary General Kofi Annan would defy the Americans and send Mr Blix off to Iraq without this issue being resolved one way or another.

Resolving it one way might lead to inspections restarting, but resolving it another way might well lead to war.