General Powell, who left the Administration in January, also said that his speech in February 2003 to the UN, making the case for war, was a painful blot on his record.

Making his most damning remarks about the conduct of the war since he was replaced by Condoleezza Rice, General Powell criticised the White House and Pentagon for their post-war planning and failure to send sufficient troops.

Asked in an interview broadcast on ABC whether he regretted his support for the war, he replied: “Who knew what the whole mess was going to be like?” He added: “What we didn’t do in the immediate aftermath of the war was to impose our will on the whole country, with enough troops of our own, with enough troops from coalition forces, or by recreating the Iraqi forces, armed forces, more quickly than we are doing now.

“And it may not have turned out to be such a mess if we had done some things differently.”

Turning to his pre-war address to the UN Security Council, when he forcefully made the case for invasion and offered proof that Iraq had weapons of mass destruction, General Powell said that he felt terrible about the claims he made. Asked whether the speech would tarnish his reputation, he replied: “Of course it will. It’s a blot. I’m the one who presented it on behalf of the United States to the world, and (it) will always be part of my record. It was painful. It’s painful now.”

General Powell, 68, did not blame George Tenet, the CIA’s Director at the time, for the misleading information, which included satellite photographs of trucks that he asserted were mobile biological weapons laboratories. Instead, he blamed lower-level intelligence analysts for not speaking out during the five days he pored over reports at the CIA as he prepared the speech.

He said: “George Tenet . . . believed what he was giving to me was accurate.” He added: “There were some good people in the intelligence community who knew at the time that some of these sources were not good and shouldn’t be relied upon, and they didn’t speak up. That devastated me.”

General Powell said that he had “never seen evidence to suggest” a connection between the attacks of September 11, 2001, and the regime of Saddam Hussein, unlike Dick Cheney, the Vice-President, who has made such a claim.

He said that there was little option now but to continue investing in the Iraqi Armed Forces. Despite his hesitation about the war — “I’m always a reluctant warrior” — he said that he was glad that Saddam and his regime had been removed.

Voicing concerns about the possibility of civil war, he said: “A way has to be found for the Sunnis to be brought into the political process. You cannot let . . . Iraq devolve into a mini-state in the north, a larger mini-state in the south and sort of nothing in the middle.”

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