Despite regrets over the failure to find WMDs, Bush said the Iraq war was justified [GALLO/GETTY]

Former US president George Bush said he has a "sickening feeling" when reflecting on the failure to find weapons of mass destruction in Iraq - nullifying the claim made by Washington as the basis for the 2003 invasion of the country.

Local media reported on Tuesday that the comments in a new autobiography is aimed at breaking his silence after making way for current president Barack Obama.

The memoir, called Decision Points, is also used to defend his record in domestic and foreign policy, while predicting that history will judge him better than US voters, who gave him low approval ratings as his second term came to an end.

Bush also wrote that the 2003 US-led invasion of Iraq was justified, saying that "the Iraqi people are better off with a government that answers to them instead of torturing and murdering them".

He also defended his decision to allow what have been called harsh interrogation techniques or torture, such as water-boarding, against terror suspects.

Bush said the techniques "saved lives" and that in response to a request by the CIA to use water-boarding against the mastermind of the September 11, 2001 attacks, he answered: "Damn right".

'In charge'

The former president also wrote in his memoir that he considered running for re-election in 2004 without Dick Cheney as his vice presidential candidate.

Bush said he wanted to put an end to assertions by critics that Cheney was the real decision-maker and to "demonstrate that I was in charge".

He writes that he spent weeks exploring the possibility of replacing Cheney with Bill Frist, a senator from Tennessee.

But he says he valued the qualities Cheney brought to their partnership and finally decided to stick with his vice president, who had agreed to run again.

Bush also expressed regret for the slow government response to Hurricane Katrina in 2005, for agreeing to reduce troop levels in Iraq after the initial invasion in 2003 and for nominating Harriet Miers, an attorney and friend, to the Supreme Court.

Source: Agencies