Tony Blair last night denied accusations that he tried to spin the findings of a highly sensitive parliamentary inquiry into the use of intelligence in the run-up to the war with Iraq.

The Tories said Defence Secretary Geoff Hoon had been left "twisting in the wind" by No 10 after a newspaper report claimed the Intelligence and Security Committee (ISC) had found he gave misleading evidence to its inquiry.

The Evening Standard in London also reported that the ISC - which issues its findings today - would clear Downing Street communications chief Alastair Campbell of "sexing up" the Government's dossier on Iraqi weapons.

The article quoted "senior No 10 officials", prompting accusations from the Conservatives that Downing Street was trying to manipulate media coverage of the ISC report.

Mr Blair dismissed the claim as "completely untrue" when he clashed with Tory leader Iain Duncan Smith during the first Prime Minister's Questions following the summer recess.

The Prime Minister's official spokesman also categorically denied Downing Street was responsible for the leak, while advising journalists to treat the Standard report with caution.

Nevertheless, he said the leak would be investigated and discussions were taking place with the ISC as to what form the inquiry would take.

"The ISC deals with matters of the utmost confidentiality and secrecy and therefore it, and those who it deals with, have to be reassured that it carries out its work in absolute confidentiality," he said.

Leaks from the ISC are extremely unusual. The committee - made up of senior MPs and peers - operates within the "ring of secrecy" with full access to intelligence material and taking evidence from the heads of the intelligence agencies.

Unlike normal Commons select committees, it submits its reports to the Prime Minister so that any security sensitive material can be blanked out before they are published.

The timing of the Standard article was acutely sensitive for the Government, coming just the day after the ISC submitted its findings to Downing Street.

Tory deputy leader Michael Ancram said that it raised serious questions about how the newspaper obtained its story.

"Once again, the Downing Street machine appears to be manipulating reports of parliamentary committees," he said.

Liberal Democrat leader Charles Kennedy said it would be "enormously surprising" if the leak had come from a member of the ISC. "It's vital for the issue of trust in the Prime Minister that this matter is cleared up quickly," he said.

The Standard journalist who wrote the report, Joe Murphy, rejected "silly conspiracy theories" that the leak was part of a plot by No 10 to "put the knife into Geoff Hoon".

"That is not the case. It is a straightforward leak," he told BBC Radio 4.

Mr Blair's spokesman also stressed that the Prime Minister's words in the Commons should be taken at "face value" when he praised Mr Hoon's leadership of the MoD during the Iraq war.

Nevertheless, the report revived speculation at Westminster that Mr Hoon was being lined up as the political "fall guy" for the Government's difficulties over the Iraq dossier and the death of the weapons expert Dr David Kelly