A DEVASTATING critique of the US intelligence failings that led to the Iraq war sparked a row in Washington last night and set the scene for Britain’s own report into its security agencies next week.

The Senate Intelligence Committee’s report made clear that CIA intelligence on Saddam Hussein’s weapons of mass destruction was wrong and largely uncorroborated. But members were split on whether the White House exerted pressure on the CIA, and passed no judgment on how the Bush Administration used the information.

The indictment of US intelligence comes as Tony Blair and the British Government brace themselves for a potentially damaging report on the quality of British intelligence.

The two reports seem certain to revive the controversy over whether the war was justified. No weapons of mass destruction have been found.

The American report said that the “group think” of the CIA extended to allies, the United Nations and other nations. The 500-page report, a year in the making, accused the CIA of overstating the threat of weapons of mass destruction, relying on dubious sources, and ignoring dissenting views.

“In the end, what the President and the Congress used to send the country to war was information that was provided by the intelligence community, and that information was flawed,” Pat Roberts, the committee’s Republican chairman, said.

Jay Rockefeller, the committee’s senior Democrat, went much further, saying that the Senate would not have given the authority for war “if we knew what we now know”.

Branding the incorrect analysis as “the biggest intelligence failure in our nation’s history”, he said that the Administration at all levels used “bad information” to bolster the case for war.

He said: “The failings will affect our national security for generations to come. Our credibility has been diminished. Our standing in the world has never been lower. We have fostered a deep hatred of America in the Muslim world that will grow. As a direct consequence our nation is more vulnerable than ever before.”

The British inquiry, by Lord Butler of Brockwell, is expected to make fresh criticism of the prominence given to the claim that Iraq could launch chemical and biological munitions within 45 minutes, possibly by suggesting that it was not well-sourced.

Mr Blair is likely to be embarrassed by criticism of the way that Downing Street became involved in the compilation of the weapons dossier, including the fact that he wrote a personal foreword, giving authority to some of the more contentious claims. Mr Blair’s decision to appoint John Scarlett as head of MI6 even though his role as chairman of the Joint Intelligence Committee was certain to be covered by the Butler inquiry, will be attacked by the Conservatives next week.

The report will go into detail on how Jack Straw, the Foreign Secretary, overruled legal advisers in his own department about whether a new UN resolution was needed to authorise the war. The Government relied on advice from the Attorney-General, Lord Goldsmith.

Ministers are hoping that Mr Blair will suffer no more than embarrassment from the report. Sources suggested yesterday that there was no “silver bullet” which would cause him severe damage but that there would be ammunition for his political critics.

The US report said that there was no evidence to suggest that members of the Bush Administration had forced their views on to the US intelligence community. But Democrats said that the committee had avoided the issue.

Carl Levin, one of the committee’s senior Democrats, said: “I think it’s clear that they were shaping intelligence in order to meet the policy needs of the Administration.”

Mr Rockefeller said that the key question which had gone unanswered was: “After the analysts and the intelligence community produced an intelligence product, how is it then shaped or used or misused by the policymakers?” Republicans on the committee have refused to consider how intelligence was handled by the White House until after the presidential election in November.

Mr Bush called it a “useful report”. “We need to know. I want to know how to make the agencies better,” he said.

George Tenet, the departing CIA chief, sounded bitter as he used his farewell address to urge colleagues to resist institutional changes implicit in the report’s conclusions.

Times Recommends

• Rio Tinto four held as China prepares case
• Diplomats must keep heads down and trousers up
• When in Rome should one make like Berlusconi?