Hopes of securing UN backing for the use of military force against Iraq suffered a setback last night as Russia indicated it would be prepared to veto a second resolution.

As Jack Straw moved to win over sceptics on the UN security council, his Russian counterpart, Igor Ivanov, said Moscow could not back any resolution which paved the way for war.

Tony Blair will today hold talks with Ivanov in a bid to persuade Russia of the need for to keep the military option open.

Ari Fleischer, president Bush's spokesman, suggested that there might not be a security council vote in any case.

"The president has made clear that the outcome, whether the UN votes or does not vote, that we will disarm Saddam Hussein with a coalition of the willing," he said.

But Britain warned that forcing the US to act outside the UN could have disastrous consequences.

The foreign secretary yesterday told France and Germany to "take care" in their opposition to war.

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

Reports in today's press suggest that the United Nations has drawn up a confidential plan to establish a post-Saddam government in Iraq.

And on the domestic front, the FT reports that there could be a series of ministerial resignations if the UK goes to war without a second UN resolution.

Adding to Blair's woes, a source tells the paper there could be "lots of resignations" from the government's legal service if military action is thought to be in breach of international law.

Colleagues of Cherie Blair at the Matrix legal chambers have issued an opinion that even with a second resolution military action could be illegal.

And a decision to lead Britain into a war against Iraq would "amount to a personal resignation from the Labour Party" and allow ordinary members to reclaim it, Tony Benn said yesterday.

But the latest MORI poll shows support for military action is increasing.

Provided the UN gives authorisation, 75 per cent would support the use of force.