Some claims about Iraq's weapons were given too much weight by the government, MPs have ruled - but they have cleared media chief Alastair Campbell of "sexing up" intelligence.
The 54-page report follows a four week inquiry
The all-party foreign affairs committee says a suggestion that Iraq could deploy chemical and biological weapons within 45 minutes should not have been given such prominence by the government.
And they say "the jury is still out" on whether the government's assessment of the threat from Iraq was accurate.
But in their 54-page verdict on how ministers made the case for war in Iraq, the MPs - in a split decision - say Mr Campbell did not make changes to a dossier on Iraq's weapons, as alleged in a BBC report.
In another finding upon which the committee were divided, the report says ministers did not mislead parliament over Iraq's weapons.
Foreign Secretary Jack Straw immediately repeated calls for the BBC to apologise for its report and "acknowledge that it got it wrong".
Mr Campbell said he was pleased the MPs had found the BBC reports "are untrue" but said he was "saddened that... they (the BBC) still refuse to admit that the allegations they broadcast were false".
But the BBC's director of news, Richard Sambrook, said the committee's report justified the decision to run the original report about the 45 minutes claim on Radio 4's Today programme.
"The committee's report clearly says there are big questions to be asked about the provenance of that claim," he said.
"It asks questions of the government and also makes comments about the assertiveness of the language of the September dossier."
Mr Sambrook said the committee was "deeply divided" about whether to exonerate Mr Campbell and the BBC stood behind the credibility of the source whose concerns prompted the original story.
In their report, the MPs made 33 conclusions and recommendations.
They argue that "the jury is still out on the accuracy" of the first dossier on Iraq, published last September.
And they say Prime Minister Tony Blair "misrepresented" the status of the second so-called "dodgy dossier" in parliament and "thus inadvertently made a bad situation worse".
The MPs accuse ministers of "hampering" their inquiry by refusing to allow them access to intelligence papers and security services personnel.
On the BBC allegation, the committee's report says that "on the basis of the evidence available to us Alastair Campbell did not exert or seek to exert improper influence on the drafting of the September dossier".
However, the MPs were split over that finding, with it passed only on the casting vote of the Labour chairman of the committee.
The committee argues that the 45 minutes claim "did not warrant the prominence given to it in the dossier, because it was based on intelligence from a single, uncorroborated source".
And they urge the government to explain why it was "given such prominence" - and say it was wrong for Mr Campbell to have chaired meetings on intelligence matters.
The report says: "We conclude that the claims made in the September dossier were in all probability well founded on the basis of the intelligence then available....although we have concerns about the emphasis given to some of them."
The MPs say some of the language in the dossier was "too assertive".
They go on: "However, we have no doubt that the threat posed to United Kingdom forces was genuinely perceived as a real and present danger and that the steps taken to protect them were justified by the information available at the time."
The report calls on the government to set out whether it still considers its claims about Iraq's weapons published in the dossier last September to be accurate.
On the second so-called "dodgy dossier" published last February, the MPs say the document was "almost wholly counter-productive" and it was "fundamentally wrong" for it to have been referred to by Mr Blair in the Commons.
The dossier contained an unattributed academic paper and such plagiarism was "wholly unacceptable" said the committee.
Tory leader Iain Duncan Smith said Mr Blair had to explain to MPs why he gave an "inaccurate impression" of the second dossier in the Commons.
In a letter to the prime minister, Mr Duncan Smith said: "You must apologise for misleading - albeit inadvertently - the House of Commons and the British people by 'misinterpreting' the dossier in Parliament."
Donald Anderson, the foreign affairs committee chairman, said he thought the prime minister should come to the Commons to apologise.
He added: "I think he should have come to Parliament way back in February and put the record straight."
Liberal Democrat leader Charles Kennedy said an independent judicial inquiry should be held into the affair.
Later, in its first official assessment of the war, the Ministry of Defence said the UK and the US had only limited intelligence about Iraqi forces in the run up to the conflict.