Tony Blair has been defended as a man of "courage and integrity" as senior cabinet members close ranks over Iraq following Saturday's anti-war rallies.

Delegates at the party's spring conference were told by Deputy Prime Minister John Prescott that the prime minister was a man they should trust.

Earlier party Chairman Dr John Reid said the government had to listen to anti-war marchers - but insisted taking no action against Saddam Hussein would signify a failure.

There is not a person in our movement who does not want to give peace a chance John Prescott

On Saturday, the prime minister refused to back down from his commitment to use force against Iraq if necessary, despite the scale of anti-war marches in central London, Glasgow and Belfast.

Organisers claimed up to two million people took part in the capital, with police estimates putting the figure "in excess of" 750,000.

Addressing conference delegates in Glasgow on Sunday, Mr Prescott said: "War is an ugly, costly, dehumanising scar on the human existence. No decent, no rational person would ever choose war over peace."

But, he continued: "History teaches us that actions against humanity by evil people in defiance of international law cannot always be stopped by persuasion, by intellectual appeal, by economic sanctions or even dire threat."

He told the audience that even if they had not agreed with Mr Blair's speech on Saturday, "you couldn't doubt his commitment to make the UN process work or his conviction that leaving Saddam in power could be inhumane".

Essential solidarity

He added that "on Sierra Leone, on Kosovo, and on Afghanistan Tony Blair acted as a leader, and deserves our trust now."

Dr Reid told BBC1's Breakfast With Frost programme the choice was not between war and peace.

The Labour chairman said: "It is between doing something to protect the world and people in Iraq, or doing nothing."

Click here to see UK protests in pictures

In his passionate conference address, Mr Blair said ridding the world of Saddam would be an act of humanity.

The consequences of leaving him in power would be paid in blood, the prime minister warned.

"If we show weakness now, if we allow the plea for more time to become just an excuse for prevarication until the moment for action passes, then it will not only be Saddam who is repeating history," Mr Blair said.

"The menace, and not just from Saddam, will grow; the authority of the UN will be lost; and the conflict when it comes will be more bloody."

Members unconvinced

And Mr Blair was dismissive of recent concessions by the Iraqi dictator, warning: "The concessions are suspect. Unfortunately, the weapons are real."

But many party members remain unconvinced.

The Conservatives have re-stated their overall support for the government's policy on Iraq, although they have criticised ministers for not making the case well enough.

Tory leader Iain Duncan Smith suggested on Sunday that global terrorism could be dealt a fatal blow if the international community removed Saddam.

He told BBC One's The Politics Show: "If the UN will stand up to this man, there is a chance that, once and for all, we may rid ourselves of terrorism and those who support it."

He also accused Liberal Democrat leader Charles Kennedy of "playing games" following his speech at Saturday's huge anti-war protest in London.

Tony Woodley, deputy general secretary of the Transport and General Workers Union, said the demonstration made it clear the prime minister was in "real trouble".

He said: "If Mr Blair does not look up now and listen to the views of the British people it could certainly bring if not the party down, it could bring him down - and that's the last thing we would wish to see happen."