A group of senior MPs is calling for a vote to decide whether Tony Blair is guilty of contempt of Parliament over his decision to invade Iraq in 2003. Conservative David Davis said he will present the motion on Thursday accusing the former PM of misleading Parliament.
Meanwhile, John Prescott, the then deputy prime minister, said he now believed the invasion was "illegal".
Mr Blair has apologised for mistakes he made but has said he stands by his decision and "there were no lies".
In his long-awaited report on the Iraq invasion, Sir John Chilcot said the legal basis for the war was reached in a way that was "far from satisfactory", but he did not explicitly say it was illegal.
But Mr Davis, a former shadow home secretary, told BBC One's Andrew Marr Show: "I'm going to put down a contempt motion, a motion which says that Tony Blair has held the House in contempt.
"It's a bit like contempt of court. Essentially by deceit."
Referring to the 2003 vote to invade Iraq, he said: "If you look just at the debate alone, on five different grounds the House was misled, three in terms of the weapons of mass destruction, one in terms of the UN votes were going, and one in terms of the threat, the risks."
He has cross-party support with SNP MP Alex Salmond saying Mr Blair's actions were "a parliamentary crime, and it's time for Parliament to deliver the verdict".
Labour leader Jeremy Corbyn said he agreed "Parliament must hold to account, including Tony Blair, those who took us into this particular war".
Asked if he would back the motion, he told the BBC: "I haven't seen it yet, but I think I probably would."
Mr Davis said if his motion is accepted by Speaker John Bercow, it could be debated before Parliament breaks up for the summer on 21 July.
He said if Mr Blair was found guilty it was unclear what actions would be taken but "the government could choose to strip him of his Privy Councillorship".
Sunday Mirror front pageImage copyright Sunday Mirror Mr Blair has repeatedly said he did not deceive Parliament.
Following last week's publication of the Chilcot report, the former prime minister made a statement to the media saying "there were no lies, Parliament and Cabinet were not misled, there was no secret commitment to war, intelligence was not falsified and the decision was made in good faith".
He did admit mistakes, saying it would be "far better" if he had challenged intelligence on Iraq's weapons in the run-up to war.
Meanwhile, writing in the Sunday Mirror, Lord Prescott said he now agreed "with great sadness and anger" with former UN secretary general Kofi Annan that the war was illegal.
He said he would live with the "catastrophic decision" for the rest of his life.
"A day doesn't go by when I don't think of the decision we made to go to war. Of the British troops who gave their lives or suffered injuries for their country. Of the 175,000 civilians who died from the Pandora's Box we opened by removing Saddam Hussein," he went on.
He also expressed his own "fullest apology" and said he wanted to identify "certain lessons we must learn".
"My first concern was the way Tony Blair ran Cabinet. We were given too little paper documentation to make decisions," he wrote. Alastair Campbell, Mr Blair's former communications chief, criticised Lord Prescott's intervention.
He tweeted: "Don't recall @johnprescott raising all these concerns till now. Odd. And given how certain people stood by him in tough times..."
The Chilcot report said estimates of the threat posed by Iraqi weapons of mass destruction were presented with a certainty which was not justified.
British troops suffered from inadequate preparation and equipment and plans for the aftermath of the war were "wholly inadequate", it concluded.