Former US president George Bush has said information obtained from terrorist suspects through "waterboarding" prevented attacks on London, saving British lives.
In his memoirs, serialised in The Times, he said the use of the controversial interrogation technique - which simulates drowning - had helped to break up plots to attack Heathrow Airport and Canary Wharf.
In an interview with the newspaper, the 43rd US president confirmed he authorised the use of waterboarding to extract information from Khalid Sheikh Mohammed, the al Qaida mastermind behind the 9/11 attack, telling the paper: "Damn right!"
Mr Bush said: "Three people were waterboarded and I believe that decision saved lives."
In the book, Decision Points, he writes: "Their interrogations helped break up plots to attack American diplomatic facilities abroad, Heathrow airport and Canary Wharf in London, and multiple targets in the United States."
The British government has long rejected the use of waterboarding, which it regards as torture. In a speech last month, the Chief of MI6 Sir John Sawers insisted that his service had "nothing whatsoever" to do with torture which he described as "illegal and abhorrent".
In the interview, Mr Bush described his close relationship with Tony Blair, but was dismissive of public opinion in Britain about the war in Iraq. "It doesn't matter how people perceive me in England. It just doesn't matter any more. And frankly, at times, it didn't matter then," he said.
Mr Bush recalled how when Mr Blair faced a possible vote of no confidence in Parliament on the eve of war, he offered him the chance to opt out of sending British troops into Iraq.
He said that "rather than lose the government, I would much rather have Tony and his wisdom and his strategic thinking as the prime minister of a strong and important ally".
However, Mr Blair told him: "I'm in. If it costs the government, fine."