The agencies were told through secret channels by Saddam Hussein’s foreign minister and his head of intelligence that Iraq had no active WMD programme, but this information was not passed to subsequent inquiries.

Tony Blair told parliament before the war that intelligence showed Iraq’s nuclear, chemical, and biological weapons programme was “active”, “growing” and “up and running” which is now clear was not the case.

A BBC Panorama programme tonight will describe how Naji Sabri, Saddam’s foreign minister, told the CIA’s station chief in Paris at the time, Bill Murray, through an intermediary that Iraq had “virtually nothing” in terms of WMD. Sabri has said in a statement that the Panorama story is “totally fabricated”.

Panorama confirms that three months before the war an MI6 officer met Iraq’s head of intelligence, Tahir Habbush al-Tikriti, who also said that Saddam had no active WMD. The meeting took place days before the British government published its now widely discredited Iraqi weapons dossier in September 2002.

Lord Butler, the former cabinet secretary who led an inquiry into the use of intelligence in the runup to the invasion of Iraq, tells the programme that he was not told about Sabri’s comments, and that he should have been reports The Guardian.

He says: “There were ways in which people were misled or misled themselves at all stages.”

In response to a comment that most misled of all was the British public, Butler replied: “Yes, I think they’re, they’re, they got every reason think that.”