Tony Blair ordered naval forces to prepare for the Iraq war before the decision to invade Iraq was officially announced, the former Royal Navy first sea lord has claimed.

Admiral Lord West, who was the naval chief when Mr Blair announced the start of the Iraq War, said “some bastard" told him to prepare for the war before the announcement was made, but that "they were looking for a reason to actually do it."

He made the claims ahead of the official report into the UK's involvement in the 2003 Iraq War, chaired by veteran civil servant Sir John Chilcot.

Lord West told Parliament’s The House magazine: “I think there had been a decision that we were going to invade Iraq, that that was going to happen, but they were looking for a reason to actually do it.

"Of course Blair and everyone else will say, 'No, we didn't make the decision until right up to it'. You can always say that, can't you?

“But I would not have told the fleets, the Royal Navy and the Marines, to be ready for war in the northern Gulf by the end of the year. I would not have sailed the Mine Counter-measures Force for the Middle East so they were in place for operations.

"You don't wake up in the morning and think that. Some bastard told me to do it. That's why I did it."

The two-million-word Chilcot Inquiry will be published on Wednesday 6 July. Sir Chilcot is not expected to take questions after outlining the findings, but the full report will be released on the Iraq Inquiry website.

The key players in the Iraq War Show all 11 1 /11 The key players in the Iraq War The key players in the Iraq War Jack Straw Jack Straw was the UK foreign secretary at the time of the Iraq invasion, and fully endorsed the decision Getty The key players in the Iraq War Geoff Hoon Geoff Hoon was Tony Blair’s defence secretary from October 1999 to May 2005 Getty Images The key players in the Iraq War Alastair Campbell Alastair Campbell was involved in the drafting of two Downing Street dossiers on the war, in September 2002 and in February 2003 Getty The key players in the Iraq War John Scarlett John Scarlett was chairman of the Joint Intelligence Committee at the time of the 2003 invasion Getty Images The key players in the Iraq War Peter Goldsmith Peter Goldsmith was Mr Blair’s attorney general from 2001 to 2007 AFP/Getty Images The key players in the Iraq War Condoleezza Rice Condoleezza Rice was named as National Security Advisor to George W Bush in 2000, becoming the first woman to occupy the post, and argued publicly in favour of the 2003 invasion Getty Images The key players in the Iraq War Colin Powell Colin Powell was Secretary of State from 2001 to 2005 Getty Images for TIME The key players in the Iraq War Tommy Franks Tommy Franks was the leading US general at the start of the Iraq war The key players in the Iraq War Dick Cheney Dick Cheney was George W Bush’s vice president from 2001 to 2009 Getty Images The key players in the Iraq War Paul Bremer Paul Bremer ran Iraq for 14 months after the invasion, appointed Bush’s Presidential Envoy in charge of the occupying forces Getty Images The key players in the Iraq War Hans Blix Hans Blix was the UN weapons inspector tasked with monitoring Iraq from 2002 to 2003 Getty Images

The report will cover almost a decade of policy decisions made between 2001 and 2009, and will look into the background to the decision to go to war, including whether troops were properly prepared, how the conflict was conducted and the planning put in place for its aftermath.

Mr Blair has said he will not comment on the report until after it is published.

The Chilcot Inquiry was called for in June 2009 by former Prime Minister Gordon Brown, who said it would be conducted to identify lessons that can be learned from the conflict.

British troops invaded Iraq in 2003 as part of an international coalition led by the US.

In the run up to the invasion, Mr Blair repeatedly claimed the Government wanted approval from the UN before any military plans were drawn up.

But after failing in efforts to secure explicit UN authorisation for military action, the coalition invaded Iraq without conforming with the UN Charter.

The military action led to the collapse of the regime of Saddam Hussein, who had ruled the country since the late 1970s.