The weapons expert David Kelly believed Saddam Hussein was less of a threat before the Iraq invasion last year than he was 10 years ago, and could only use his supposed weapons of mass destruction in "days or weeks'', rather than 45 minutes as the Government has claimed.
Dr Kelly's views were revealed yesterday in a hitherto unshown interview with BBC's Panorama, which took place just a month after Tony Blair made the 45-minute assertion in his dossier last September.
Meanwhile, the International Institute of Strategic Studies (IISS) has commissioned an independent authority to review its assessment of Iraq's military capability before the US and British went to war.
The IISS report on Iraq, published less than two weeks before the Government's dossier of 24 September, forecast Saddam Hussein would be prepared to use chemical weapons against an invader, and canvassed the likelihood that Iraq had stockpiles of chemical and biological weapons.
Dr Kelly, who allegedly killed himself after being revealed as the source for Andrew Gilligan's report that the Government had "sexed up" the dossier, believed Iraq was a real threat. But he also maintained British intelligence had major gaps in knowledge about the country's WMD, and that Saddam would only use them if he was attacked as a last resort.
Questioned by Panorama, Dr Kelly said: "Iraq's intrinsic capability has been reduced since 1990-91.'' Speaking about Saddam's supposed WMD arsenal, he continued: "Even if they are not actually filled and deployed today, the capability exists to get them filled and deployed within a matter of days or weeks.''
Asked how Iraq might launch a chemical or biological attack, Dr Kelly said: "The actual form, we don't really know.He'd have been planning to develop them and have better and more effective systems and those we are completely unsighted of, and we are also unsighted as to whether that work has continued since 1991 to this very day.''
The scientist also suggested Saddam might have only used those weapons in self-defence. "I think he'd use them. Of course, what is more difficult to answer is how and under what circumstances he would use them,'' he said.
Dr Kelly also stated Iraq's neighbours, such as Iran and Israel, were a threat.The September dossier implied British bases in Cyprus were within the range of Iraqi chemical and biological weapons.
Panorama accused Gilligan of inaccuracies in his report about Dr Kelly, and criticised the BBC management for standing by him without carrying out an internal investigation.
The programme maintained Gilligan did not have enough evidence to back up his charge that the Government had deliberately inserted the false 45-minute threat. Instead, it concluded that John Scarlett, the chairman of the Joint Intelligence Committee, tasked with drawing up the dossier, had acquiesced too readily to pressure from Downing Street.
The Panorama special was broadcast a week before Lord Hutton presents his report. John Ware, the veteran investigative reporter who presented the programme, said the scheduling was decided by Lorraine Heggessey, the controller of BBC1. But, according to some reports, Greg Dyke, the director general of the corporation, was said to have been "surprised'' by the peak-time airing.
Mr Ware attacked senior managers for failing to check Gilligan's notes, which were the basis for accusing Alastair Campbell, then the Prime Minister's communication chief, and Downing Street of doctoring the dossier. He concluded: "The director general and his senior executives bet the farm on a shaky foundation.''
The BBC said it had passed on tapes of the interview to the Hutton inquiry but no reference was made to it during the proceedings. Filmed on 29 October 2002, it was never broadcast.
The shadow Foreign Secretary, Michael Ancram, said last night: "It is a great shame that Dr Kelly's remarks on this matter were not presented publicly as evidence to the Hutton inquiry. His comments do place his views at odds with those presented in the Government's September dossier.''Reuse content