A survey of Labour backbench MPs for the BBC suggests an overwhelming majority do not believe there is enough evidence to justify war on Iraq.

MPs made their feelings clear as Tony Blair said Britain must be prepared to pay a "blood price" to secure its special relationship with the US.

There's a very strong feeling that this prime minister has largely cut himself off from listening to Labour grass roots opinion

Mark Seddon Labour's national executive committee

On Friday Foreign Secretary Jack Straw warned the world's patience with Iraq had its limits.

In a speech in Birmingham he also said military action against Iraq could not be ruled out.

Of 100 MPs who agreed to take part in a survey for BBC Radio 4's Today programme, almost 90% said there were currently insufficient grounds to declare war on Iraq.

Eighty-six said a debate should be held in the Commons before any decision was taken.

Commentators told the programme the growing division between the prime minister and his MPs could lead to a split in the party.

Mark Seddon, a member of the party's national executive committee, said there was "hardly a voice" to be heard in support for a pre-emptive strike on Iraq.

"There's a very strong feeling in the Labour Party that this prime minister has largely cut himself off from listening to Labour grass roots opinion," he told Today.

Iraq is still believed to have Scud missiles

More than half of the MPs who responded called for a vote on the issue at the Labour party conference later this month.

And some backbenchers were further worried by Mr Blair's comments in an interview with the BBC Two programme Hotline to the President, to be screened on Sunday, in which he was asked whether the UK would be willing to pay the "blood price" by committing troops to a US-led war.

The prime minister said that while Britain was not America's puppet, the US "needs to know, 'Are you prepared to commit, are you prepared to be there when the shooting starts?'"

And the answer to that was "yes", he added.

Evidence

On Thursday night, almost 100 British and US war planes attacked an air defence base in the no-fly zone in western Iraq.

Veteran Labour MP Tam Dalyell, Father of the House of Commons, said that "it is deeply wrong to sleepwalk into war with additional strikes" such as the latest one.

"Before he talks about blood price, the prime minister has a moral duty to recall the House of Commons.

"It is important to recall Parliament so that the diversity of opinion in Britain is clear to American decision-makers."

Glenda Jackson: 'Let's see the evidence'

Labour MP Glenda Jackson said it was "ludicrous" that it had not been debated in the Commons.

She said her constituents were expressing concerns hourly "about what they see as this country engaging in a military action without the hard verifiable evidence that, appalling though Saddam Hussein and his regime may be, they are at this moment a clear and present danger to the rest of the world".

"Let's see the evidence," she added.

MPs were asked if they "currently" thought there was enough evidence for a war.

Ian Davidson, MP for Glasgow Pollock, is among those who say they could be persuaded to support action if the evidence in the dossier on Saddam Hussein is strong enough.

"I don't believe that we should rule out military action...but I want to see the evidence," he said.