Trade and Industry Secretary Patricia Hewitt has made the government's first direct apology for using inaccurate intelligence to justify the Iraq war.
Ms Hewitt stood by the decision to go into Iraq
Appearing on BBC One's Question Time, Ms Hewitt said she was speaking on behalf of the entire Cabinet.
"All of us who were involved in making an incredibly difficult decision are very sorry and do apologise for the fact that that information was wrong."
But she added: "I don't think we were wrong to go in."
Ms Hewitt was responding to members of the audience who challenged her comment that Prime Minister Tony Blair had already apologised for the inaccuracy of the intelligence.
At Labour's annual conference last week, Mr Blair said: "I can apologise for the information that turned out to be wrong, but I can't, sincerely at least, apologise for removing Saddam."
Ms Hewitt told Question Time: "What we said at the time and in the dossier about the stockpiles of weapons was wrong and we've apologised for that."
But one audience member shouted out: "You haven't".
Another woman said of Mr Blair's conference comment: "That is saying 'I'm able to apologise but I'm not actually apologising'."
Conservative policy co-ordinator David Cameron, who was on the Question Time panel, said it was "seriously refreshing" that Ms Hewitt used "the S- word".
"They are apologising for the wrong thing," he told BBC Radio 4's Today.
"Yes, the information about WMDs was wrong... What the apology is required for is the way in which the information was presented to Parliament."
Mr Blair had told MPs the information was "extensive, detailed and authoritative", said Mr Cameron, but the Butler report into the intelligence suggested it was "sporadic and patchy".
What had been needed in such a serious situation was "the whole truth and nothing but the truth," Mr Cameron added.
Liberal Democrat foreign affairs spokesman Sir Menzies Campbell echoed Mr Cameron's comments.
"It is not the intelligence for which we need an apology but the way in which it was used," he said.
"Patricia Hewitt may have said 'sorry' but the only apology that would count would be from the prime minister acknowledging that the government took us to war on a flawed prospectus."
On Thursday, the Iraq Survey Group released a report saying it had found no evidence Saddam Hussein had chemical, biological or nuclear weapons when Iraq was invaded.
But Mr Blair highlighted its finding that Saddam hoped to revive a WMD programme once sanctions were lifted.
BBC political correspondent James Hardy said the prime minister's conference statement had annoyed many Labour activists.
He said: "Ms Hewitt's unexpected intervention might appease some critics, others will say it's not an apology for the intelligence that they want, but an apology for the war."
A Downing Street spokesman denied that Ms Hewitt had gone further in her apology than Mr Blair.
Speaking during a trip to Ethiopia, Mr Blair said the report showed Saddam "never had any intention of complying with UN resolutions" and was "doing his best" to get around UN sanctions.
He added: "And just as I have had to accept that the evidence now is that there were not stockpiles of actual weapons ready to be deployed, I hope others have the honesty to accept that the report also shows that sanctions weren't working."
The Liberal Democrats have called on Mr Blair to make a Commons statement on the ISG report, while the Tories say it shows the prime minister has not been honest.
Liberal Democrat leader Charles Kennedy said: "The prime minister must come to the House of Commons and make a full statement as a matter of urgency to explain why this country went to war on a false premise."
Conservative leader Michael Howard said: "I don't think he [Mr Blair] told the truth about the intelligence he received."