Liberal Democrat leader Charles Kennedy has reacted furiously to suggestions by Jack Straw that his policies would have strengthened Saddam Hussein.
Charles Kennedy was furious about the jibe
Mr Kennedy accused the foreign secretary of insulting the millions of opponents of the war by suggesting they were supporters of the Iraqi leader.
He accused the government of trying to rewrite the history of the conflict.
Mr Straw said the Lib Dems "dare not admit" their policy would ultimately have created a stronger Saddam.
He was repeating a line of attack used by Tony Blair in last week's prime minister's questions when parliamentary procedures denied Mr Kennedy the chance to respond.
The foreign secretary told BBC Radio 4's Today programme: "We have a
responsibility for sorting the situation [in Iraq] out.
"Those who opposed the military action, however, also have their
"As of March 2003, the possibility of securing a weakened Saddam by effective inspections and an ultimatum wasn't on offer.
"The choice was between our course or a strengthened Saddam Hussein, who for sure once the sanctions had degraded - as they were doing - and the troops had left, would have emerged more powerful, carrying out his torture and his tyranny within Iraq and threatening the region as a whole.
"That, I'm afraid, is the position of the Liberal Democrats which dare not
speak its name in terms of their policy."
Mr Kennedy's aides say he was so "infuriated by the smear" that he rang up the Today programme to get his demand for an apology on the airwaves.
The Lib Dem leader called Mr Straw's remarks "scandalous and gratuitous".
"I want an apology today from the foreign secretary for what he has said about us and what he has said about the millions of people in this country who have agreed with us," he said.
"To try to suggest or imply, as he did, that somehow those of us who were
against the war were, in fact, covertly in favour of some form of strengthened Saddam Hussein is an absolute insult to the integrity as well as the intelligence of people."
Mr Kennedy said opponents of the war, including United Nations chief weapons inspector Hans Blix, had never argued for Saddam Hussein to be strengthened.
He accused Mr Straw and the government of persistently trying to shift the goal posts.
"He is now saying that the only options were to do nothing and allow Saddam to strengthen his position or to go to war," he continued.
"That is not an accurate version of history, and it is one which the prime
minister and foreign secretary should recant."
Later Mr Kennedy repeated his apology demand in a letter to Mr Straw.
As he sent the letter, he said: "The foreign secretary is suggesting opponents of the war were Saddam supporters...
"This is a shoddy way to conduct our politics. Instead of smearing his political opponents the foreign secretary should apologise."
But the foreign secretary looks unlikely to meet the demand.
An aide to Mr Straw: "The foreign secretary is absolutely right to point out that the inevitable consequence of Liberal Democratic policy would have been to leave a strengthened Saddam Hussein in Iraq.
"As he has said many times before, the government fully accepts the consequences of the decision it took in March 2003.
"It is time for Charles Kennedy to accept the consequences of his decision too."