Tony Blair should listen to the "very, very grave doubts" felt by the public over war with Iraq, a former Labour minister has warned.

Doug Henderson, who was a Foreign Office minister, urged the prime minister to be a conduit between European leaders and the US administration.

They don't want to be seen as some kind of posse running after George Bush's enemies Doug Henderson

At the same time Liberal Democrat leader Charles Kennedy criticised the government for giving out "mixed messages" over the prospect of military action.

And, following a swathe of peace protests across the world on Saturday, he also refused to rule out joining a future anti-war demonstration.

But the defence secretary, Geoff Hoon, has kept up the pressure on Saddam Hussein by warning that the discovery of "persuasive evidence" by inspectors that he had weapons of mass destruction might be enough to justify war.

Time warning

The chief UN inspectors have arrived back in Iraq to press for more active compliance in what is being seen as a final opportunity for a change in attitude before they present their findings to the UN on 27 January.

Clearly we believe there are weapons of mass destruction in Iraq Geoff Hoon

No 'smoking gun' needed in Iraq - click here for full story

But Mr Kennedy said he feared that the US had no appetite to allow Hans Blix and his team extra time for their work in Iraq even if it was requested.

He also told BBC's Breakfast with Frost programme: "I don't think that the government are helping the case in this country - and the American administration [is] even worse - by sending out such mixed messages."

"We are deploying British troops into the region at the moment and they are not being given a clear idea - are they liable to be engaged in conflict or are they not?"

Mr Kennedy said it was vital that the US and UK continued to take the UN route.

Mr Henderson said on GMTV: "I don't think public opinion wants to see our troops going into a war that public opinion believes is unjustified - the prime minister needs to recognise that.

'Generals opposed'

He added: "I think if he joins George Bush in an invasion of Iraq, especially if there is doubt in the Security Council of the United Nations, then he won't command that support and he will put himself in a position he hasn't previously put himself in.

"Other world leaders are not putting themselves in that situation and I believe he should think a wee bit more broadly than just following an American view."

Mr Henderson also suggested there was opposition in the British military for a war, with generals not wanting to be seen as "some kind of posse running after George Bush's enemies".

His comments came after peace campaigners held a series of protests across the UK as part of a global show of opposition to war with Iraq.