Union leaders are calling for a special meeting of the Trade Union Congress to debate the Iraq crisis.

Transport union leaders Mick Rix and Bob Crow said Tony Blair was failing to convince the British people that military action against Iraq was necessary.

The Liberal Democrats are looking for cheap votes Iain Duncan Smith Tory leader

Meanwhile Tory leader Iain Duncan Smith accused his Lib Dem rival Charles Kennedy of looking for "cheap votes" after he said he would take part in next Saturday's anti-war rally in London.

As splits appeared within the Nato alliance, UK Defence Secretary Geoff Hoon told the Guardian newspaper that British troops would play a key role in peacekeeping and rebuilding Iraq after any war.

Blair risking all

Speaking at a Westminster press conference organised by the Stop the War coalition Mr Crow, from the RMT, predicted voters would use the local elections in May to register their disapproval at Mr Blair's policy on Iraq.

Likening Mr Blair to the former Romanian leader Nicolae Ceausescu, Mr Crow said public opinion was being ignored, but people could change things by taking part in Saturday's protest march.

Bob Crow: Anti-war

Paul Mackney, leader of the college lecturers' union NATFE, said Tony Blair's premiership would fall if he didn't change his mind on Iraq.

Mr Duncan Smith, whose Tory party is broadly supportive of the government's policy on Iraq, criticised Lib Dem leader Charles Kennedy's stance.

He said: "It is a time for leaders to lead and not to play games. The Liberal Democrats are looking for cheap votes. This isn't the time to do that. It is not serious politics.

"They want it both ways. They want to ride on the back of public concern."

Lack of clarity

Mr Kennedy, speaking on BBC One's Breakfast with Frost programme on Sunday, said he would be happy to take part in the anti-war march to set out his party's view.

He said his was a "pro-UN case", adding: "It is not anti-war come what may."

Our forces are flexible, and they have been designed in a way to provide a number of military options Geoff Hoon Defence Secretary

A spokesman for the Stop the War coalition welcomed Mr Kennedy's willingness to join the march and said an invitation had been issued to the Liberal Democrats.

Mr Kennedy called on Tony Blair to make a more persuasive case for tackling Saddam Hussein, saying there was a lack of clarity in the government's approach.

Preserving peace

Defence Secretary Geoff Hoon said British troops' peacekeeping abilities had been shown while undertaking duties in Kosovo and Afghanistan.

"Our forces are flexible, and they have been designed in a way to provide a number of military options, including the prospect of, in the first place, ensuring security in the immediate aftermath of a military operation," Mr Hoon said.

Kennedy said his is a "pro-UN" position

The troops would then engage in "preserving the peace and helping the process of rebuilding Iraq as a member of the international community, something which they've shown previously they are extremely good at".

This Friday, when Hans Blix and Mohamed ElBaradei present their key report to the UN Security Council, will be "a very significant day", said Mr Hoon.

Despite any military conflict being led by the US, British troops would "ultimately" be under the control of the Prime Minister, the Defence Secretary said.

If you go to war in modern times you need the broad bulk of the public behind you Kenneth Clarke

Former Cabinet minister Mo Mowlam said on Sunday she too will join the protests in London on 15 February.

Mr Blair was also warned by senior Tory Kenneth Clarke that he faced another Vietnam if the public could not be persuaded.

Invitation

EU External Affairs Commissioner Chris Patten said action against Iraq risked tearing the Gulf state apart and destabilising the whole region.

Mr Clarke told BBC Radio Four's The World This Weekend that Mr Blair would "pay" if he failed to persuade the British public that there was a proper case for war with Iraq.

"If you go to war in modern times you need the broad bulk of the public behind you.

"It is a broad analogy to draw between America and Vietnam but what destroyed America in Vietnam was the bulk of the American public were never really persuaded of the case for fighting in Vietnam at all."