Russia has signalled that it will refuse to back a second UN resolution sanctioning force in Iraq.

The country's foreign minister, Igor Ivanov, said he could not back a military offensive against Baghdad.

The move is a setback to the government - which had hoped the Security Council may back down and support a second resolution.

Whilst he said relations between Britain and Russia "had never been better", Straw admitted the two countries had a difference of opinion on how to disarm Iraq.

He said both nations "shared the same objective" but admitted there are "outstanding questions" about how to achieve disarmament.

Ahead of talks with Straw Ivanov said that "Russia will not support any decision that would directly or indirectly open the way to war with Iraq".

Signalling that Moscow would be prepared to veto the UK's resolution, he told the BBC: "Abstaining is not a position Russia can take. We have to have a clear position and we are for a political solution."

"I do not rule anything out because the right of veto can be used by any permanent member of the Security Council including Russia. If necessary, Russia can resort to using this right."

Ahead of a meeting with Ivanov, foreign secretary Jack Straw attacked Iraq's attempts to divide international opinion.

Straw said Saddam Hussein was making "expendable" concessions to split opinion in the West.

"It is clear to us that Saddam Hussein believes that he can once again divide and outwit the international community through a pretence of cooperation," he said."We cannot afford to send him any signal that he's close to success."

The foreign secretary added that there would be negative consequences if the US was forced into acting alone.

"We will reap a whirlwind if we push the US into a unilateralist position," he said.

The meeting between Straw and his Russian counterpart came as ministers embarked on an 11th hour diplomatic offensive.

Moscow and Paris are continuing to insist that weapons inspectors must be given more time before a military option can be considered.

Tuesday's talks came amid increased speculation that Britain and the US are preparing to go it alone if the UN blocks the second resolution proposed by the UK, America and Spain.

But Labour backbenchers have warned Tony Blair that his leadership will be in doubt if he goes to war without the express consent of the UN security council.

Britain hopes that Friday's report by Hans Blix will confirm that Saddam is still frustrating UN weapons inspections.

News that Saddam has destroyed more of his al-Samoud II missiles has, however, led to speculation that the Iraqi regime is beginning to cooperate with the inspection teams.

Downing Street has continued to insist that Saddam is playing games with the international community.

"In 15 weeks, the inspectors have not been able to close a single outstanding issue," said a spokesman for the prime minister.

However the government has denied suggestions that it is now engaged in a "slide to war".

Former Labour minister Doug Henderson said that increased activity in the no-fly zones and the deployment of US Air Force B-52 bombers was evidence that war was imminent.

"The Pentagon has acknowledged that the previous policy of attacking Iraqi military capacity that threatened our planes has now been changed to attacking any Iraqi military capacity," he said.

"If Downing Street believe that there is a different interpretation, then it is high time that they got their act together."