The prime minister has expressed his full confidence in Geoff Hoon despite claims that he gave "potentially misleading" information to MPs.

Tony Blair's intervention came after a powerful committee of MPs and peers raised concerns about the defence secretary's actions.

Whilst the intelligence and security committee said Hoon did not "lie", they were "disturbed" by his actions. In a bid to shore-up support for the embattled minister, Number 10 insisted Hoon would remain in post.

"Geoff Hoon was a strong secretary of state at an important moment for this country," said a spokesman.

"He continues to do an impressive job with the difficult reconstruction and security issues that the coalition is facing in Iraq at the moment."

Downing Street's intervention came as Iain Duncan Smith called for the defence secretary's resignation.

The opposition leader said the committee's findings were "damning" and insisted the minister's position was now untenable.

"Either he should resign or the prime minister should dismiss him and dismiss him now," Duncan Smith said.

In a contrite statement to MPs during a Commons debate on defence, Hoon expressed his regret at any "misunderstandings".

"I want to make quite clear that I had no intention whatsoever of being other than open and straightforward with the committee and I regret any misunderstanding that might have arisen," he said

"As far as my own position is concerned, the committee state fairly that I did inform them of the dispute within DIS [Defence Intelligence Staff] about the way the 45 minute claim was described in the dossier.

"The committee however believe that the failure to disclose specifically that the views of the two DIS staff had been recorded in writing was unhelpful and could have potentially misled them as to the nature of the dispute.

"I recognise, given the focus on these issues, that it would have been helpful to the committee if I had mentioned specifically that the dispute was recorded in writing."

Shadow defence spokesman Bernard Jenkin was dismissive of Hoon's abuse of the spirit of parliamentary procedure.

"I believe his attempt to brush aside the question of his conduct will serve him ill," he said. "The secretary of state is discredited and should go."

But Michael Mates, a Conservative member of the parliamentary committee, said that following his statement the defence secretary should be treated "generously" by MPs.

Responding to the report, Jack Straw conceded there were "lessons to be learned" but denied that Hoon would be forced out of office.

"I am in do doubt that the defence secretary should and will remain in his post," he said. "He has every confidence of the prime minister and his colleagues."

The clash came as the secretive committee of MPs and peers published its report on the government's dossiers on Iraq.

The committee criticised the defence secretary's "initial failure" to disclose that two members of the Defence Intelligence Staff (DIS) had expressed unease about claims contained in the dossier.

"We regard the initial failure by the MoD to disclose that some staff had put their concerns in writing to their line managers as unhelpful, potentially misleading," said the report.

"We are concerned that after the first evidence session which did not consider all the concerns raised by DIS staff the defence secretary decided against giving instructions for a letter to be written to us outlining the concerns."

The committee made clear that its concerns related not just to the defence secretary but also the conduct of some senior officials.

In his first appearance before the committee, which meets in private, Hoon conceded that there had been debate among staff members.

But he decided against releasing information which would have revealed that some officials had expressed strong unease about the content of the dossier.

Whilst the report will add to the pressure on the embattled minister, committee chairman Ann Taylor said Hoon's position was not at stake.

"At no point in this document do we call for his resignation," said Taylor.

"He did not tell us lies. He told us... there had been a dispute and he was explicit about the fact there had been a dispute."

Taylor stressed that the report did not judge whether the decision to go to war was correct.

But it did examine whether intelligence was correct and "accurately reflected" in government publications.

The MPs and peers had examined over 12 years' of Joint Intelligence Committee assessments on Iraq, dating from Saddam's invasion of Kuwait in 1990.

Evidence was taken from ministers, officials and the intelligence agencies.

Committee member Michael Mates said there were "lessons to be learned" from government attempts to publish sensitive intelligence information.

"With hindsight, there are lessons to be learned but at the end the report concludes everyone did their best," he said.

Alan Beith said that members had "looked at the facts of the intelligence and how it was handled".

He said the committee had unanimously determined that there was no orchestrated attempt at deception.

"This was not a conspiracy to deceive, but the degree of weight placed on the intelligence failed to highlight the gaps in the intelligence," he said.

Leaked sections of the report had on Wednesday claimed that Hoon gave "misleading" and "unhelpful" evidence to MPs.

Amid media debate over who may have leaked sections of the report to the Evening Standard newspaper, Taylor denied that the committee was responsible.

She said she was "100 per cent confident that no member of this committee has been leaking".

And Taylor added that there were "distinct differences" between the leak and the final report.

"Not only would the committee not leak, but it would not leak inaccurately either," she said.

The leak is now the subject of an investigation ordered by Number 10.