Tony Blair's No.2 Prescott holds his hands up over 'illegal' Iraq war
The Iraq War was illegal, according to Lord Prescott, the deputy prime minister at the time of the 2003 invasion.
The Labour heavyweight used his strongest language yet to condemn Tony Blair's decision to take part in the Iraq War, a decision he supported at the time.
Lord Prescott's comments come days after the publication of the long-awaited Iraq Inquiry report by Sir John Chilcot.
Writing in The Sunday Mirror the peer said: "I will live with the decision of going to war and its catastrophic consequences for the rest of my life.
"In 2004, the UN secretary-general Kofi Annan said that as regime change was the prime aim of the Iraq War, it was illegal.
"With great sadness and anger, I now believe him to be right."
Lord Prescott said the Chilcot report was a "damning indictment of how the Blair government handled the war - and I take my fair share of blame".
"As the deputy prime minister in that Government I must express my fullest apology, especially to the families of the 179 men and women who gave their lives in the Iraq War."
He also welcomed current Labour leader Jeremy Corbyn's decision to apologise on behalf of the party for the war.
The Chilcot report strongly criticised the way former prime minister Mr Blair took the country to war in 2003 on the basis of "flawed" intelligence with inadequate preparation at a time when Saddam Hussein did not pose an "imminent threat".
Sir John also said the way the decision about the legal basis for the war was reached was "far from satisfactory", but the report did not rule on the legality of the military action.
Lord Prescott said he had concerns about how Mr Blair ran his government, with Cabinet ministers given "too little paper documentation" to make decisions.
He also said intelligence reports were based on "discussions at receptions and prejudiced sources", amounting to "tittle-tattle, not hard evidence".
Meanwhile, a senior Tory has said the public wants to see Tony Blair punished, as MPs prepare a Commons motion to find the former prime minister in contempt of Parliament.
David Davis said "quite a lot" of MPs already support the motion which will claim Mr Blair deceived MPs over the invasion.
He intends to put the motion before Speaker John Bercow on Thursday, and if granted, MPs could debate it on July 18 or 19, before parliament breaks up for the summer.
Mr Blair has defended the decision to oust Saddam.