Clare Short has called on Tony Blair to resign because she says he deceived the British people over the Iraq war.
Clare Short said Mr Blair's prospects were 'not looking good'
She accused the prime minister of risking his own legacy because of an obsession with "his place in history".
She predicted he would not lead Labour into the next election and urged him to resign for the honour of Britain.
Ms Short was international development secretary before the Iraq war but left the cabinet afterwards in protest.
Ms Short first called on Mr Blair to resign shortly after her resignation last May.
In a wide-ranging interview on Sunday with Sky News TV, she also said it was "deeply dishonourable" for Labour to have broken pledges on top-up fees.
Her criticisms were echoed by Labour left-winger Diane Abbott, who told the same programme Mr Blair has risked backbench rebellions by making loyal MPs feel like
"pillocks" over the Iraq war.
"I never believed this thing about missiles being ready for fire in 45
minutes but sadly some of my colleagues did and they are the ones that are most
bitter and disgruntled," she said.
Ms Short suggested that Mr Blair had behaved worse than John Profumo, a cabinet minister who resigned in 1963 over his affair with Christine Keeler.
"Profumo lied about having an affair with a prostitute and had to resign," she said.
"If you are going to start getting into deceit when you are going to war and risking
human life it has gone too far."
She said the intelligence agencies knew Saddam Hussein did not have weapons of mass
destruction - the premise for the war.
Going to war without the second UN resolution had been a disaster, Ms Short
She had not ruled out the use of force but it had to have UN backing, adding that there were other ways to get rid of Saddam.
"We could have done it right but I think what Tony did was promise [US President George W] Bush he
would be with him come what may, promise us a second resolution".
She said what followed was "deceit and all the disgruntlement in the UK and the failure to prepare for afterwards which is a complete disaster for the Middle East, for Iraq, for the
Ms Short told Sky's Sunday with Adam Boulton that intelligence agencies did not
believe Saddam Hussein had nuclear weapons, but thought he was determined to have
Tough time ahead
"No one thought there was some imminent danger. That was all talked up and
talked up to a point of deceit," she said.
"I think he (Mr Blair) thought it was an honourable thing to do and he
thought it was important to stick with the US and not let them be alone.
had to tell a few lies on the way it was for a good cause. I think he thought it
But Ann Clwyd, Mr Blair's special envoy to Iraq, later defended the Prime Minister's handling of the war saying the regime had to be toppled on human rights grounds "regardless of any other argument".
She told Sky News: "Do you just allow a country to carry on killing its own people, to use chemical weapons against its own people, to have mass disappearances of people?
"Anybody who has seen these mass graves and can still say this regime should not have been toppled, I think are in a very difficult situation to justify their views."
Ms Short went on to say it was unlikely Mr Blair would survive to take Labour into the next
election, and predicted difficulties ahead in the Hutton Inquiry report, the top-up fees revolt, and European Parliament elections in June.
"He is not looking good. I hope for his sake, but most particularly for the
honour of the country and for renewal of the Labour Government, I very much he
steps down gracefully."