Tony Blair's case for war suffered a fresh blow ahead of the report on intelligence failings in Iraq, it was reported last night.

Spy chiefs have retracted information that Saddam Hussein had continued to produce weapons of mass destruction, the BBC said.

The Prime Minister's evidence to the Hutton inquiry and claims about Iraqi WMD were also questioned by BBC1's Panorama.

His September 2002 dossier stated that: "Iraq has continued to produce chemical and biological agents."

This was a central plank of Mr Blair's case that the action was needed to counter the "current and serious" threat from Saddam.

However, in a rare move MI6 have now withdrawn it, a senior intelligence source told Panorama.

Mr Blair has already admitted that Iraqi WMD may never be found ahead of Lord Butler's report on intelligence failings.

However, he insisted it would have been wrong to suggest that Saddam did not pose a WMD threat.

Downing Street refused to comment ahead of the Butler report on Wednesday.

The Panorama claim came from a single, anonymous intelligence source but meets new BBC guidelines introduced in the wake of the Hutton report into Iraq mole Dr David Kelly's death.

Former senior secret service figures have gone on the record with their criticisms of Mr Blair in the programme, screened last night.

Dr Brian Jones, a retired Defence Intelligence staff (DIS) branch head, called for the retracted intelligence to be published.

That would show "what exactly it was and what was going on", he said.

Dr Jones also said he was confused by Mr Blair's evidence to the Hutton inquiry which cleared No. 10 of sexing-up intelligence.

The PM told the Hutton inquiry that a tremendous amount of information about Iraq's weapons of mass destruction had crossed his desk.

Dr Jones, a long-standing critic of the Government's Iraq dossier, said he couldn't relate to that account.

"Certainly no one on my staff had any visibility of large quantities of intelligence of that sort," he told the programme.

John Morrison, the former Deputy Chief of DIS, questioned Mr Blair's claim that the threat from Iraq was serious and current.

When the PM told that to MPs, he told the programme that he could "almost hear the collective raspberry going up around Whitehall".

Liberal Democrat leader Charles Kennedy said the arguments at the top that led us into war must be faced up to.

He said: "What Tony Blair should do this week is admit that political judgements of the highest kind were got wrong over Iraq.

"I don't want to see the intelligence community become the scapegoats for this."