A US envoy is beginning a mission to persuade France and Russia to back a new tough draft UN resolution on Iraq.

The envoy, Marc Grossman, is due to visit Paris on Friday and Moscow on Saturday.

All of us, and many others in Congress, are united in our determination to confront an urgent threat to America

George W Bush

Russia and France are among the five permanent members of the UN Security Council who have veto powers - alongside the US, Britain and China.

The draft resolution - sponsored by the US and Britain - is believed to contain clauses that could provide the legal backing for possible military action on Iraq.

"The resolution, or resolutions, must be strong enough... so that they produce disarmament and not just inspections," US Secretary of State Colin Powell told senators on Thursday.

But he admitted there were still difficulties getting agreement from Russia and France.

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Where key nations stand on Iraq

Moscow is opposed to the use of force against Baghdad, and insists no new resolution on Iraq is needed.

French President Jacques Chirac has proposed a two-step process, in which the resolution would call for unfettered access and co-operation with inspections and would be followed by a second one authorising force should Iraq defy the Security Council.

On Thursday, President Chirac met visiting Chinese Prime Minister Zhu Rongji.

"China approves the two-step approach proposed by France," a spokeswoman for Mr Chirac said.

Mr Powell has warned that the US was prepared to go it alone if it could not get the UN's backing.

'Recipe for failure'

The wording of the US-British draft has not yet been released officially.

Putin favours the return of UN inspectors

But the BBC's Jon Leyne at the State Department says that it is clearly very tough, with two separate clauses that could provide the legal backing for military action against Iraqi President Saddam Hussein.

French Prime Minister Jean-Pierre Raffarin said that the UN should do everything possible to avoid a war in Iraq, which he said was "always the last option".

But Mr Powell called such an approach "a recipe for failure".

Our correspondent says it is hard to see how France and Russia would end up vetoing a resolution that the US want so much.

Nevertheless, he says it sounds as if they are playing tough, holding out for more concessions from Washington.

On Wednesday, Defence Secretary Donald Rumsfeld added his weight to the US campaign, by again asserting that there have been high level contacts between al-Qaeda and Iraq over the past decade.

He said the United States had credible evidence they had sought contacts in Iraq who could help them acquire weapons of mass destruction.

Congress resolution

As Washington steps up its pressure for a new UN resolution, President George W Bush has said the US Congress was close to agreeing a "tough" resolution on Iraq.

Bush rallied Congress for decisive action

Speaking after talks with leaders of both the Republican and Democratic parties on Thursday, Mr Bush said Congress would soon speak with one voice.

The president is seeking authorisation to take military action against Iraq - but there is an intense debate in Washington between his supporters and critics on the precise wording of a congressional resolution.

Many Democrats have misgivings about Mr Bush's policy on Iraq.

However, the party's leaders have indicated that they would support a resolution authorising the use of force against Iraq, and help get it approved before November's mid-tern elections