Straw rejected legal advice over Iraq war

But a belligerent Mr Straw insisted that he had given serious attention to a warning from his former senior legal adviser Sir Michael Wood that the conflict would be a "crime of aggression" unless Britain achieved another UN security council resolution.

The Chilcot inquiry into the war has heard that Mr Straw, who was foreign secretary at the time of the 2003 invasion, rejected Sir Michael's advice.

But Mr Straw said in a statement to the inquiry that it would be a "fundamentally flawed" system if ministers were obliged to accept all the legal advice they received.

He wrote: "Far from 'ignoring' this advice, as has been suggested publicly, I read Sir Michael's minute with great care and gave it the serious attention it deserved.

"So much so that I thought I owed him a formal and personal written response rather than simply having a conversation with him."

The inquiry has heard that Sir Michael, former senior legal adviser at the Foreign Office, took issue with Mr Straw in January 2003 over his assertion in a meeting with US vice-president Dick Cheney that Britain would still be "OK" if it failed to get a second resolution.

He wrote to the then foreign secretary in a memo: "To use force without security council authority would amount to a crime of aggression."

Mr Straw replied: "I note your advice but I do not accept it."

Sir Michael told the inquiry: "He took the view that I was being very dogmatic and that international law was pretty vague and that he wasn't used to people taking such a firm position.

"When he had been at the Home Office, he had often been advised things were unlawful but he had gone ahead anyway and won in the courts."

Sir Michael's deputy Elizabeth Wilmshurst, who resigned in protest against the war, said that the Foreign Office lawyers were united in their belief of the need for a second resolution.

Stop the War Coalition convener Lindsey German said: "It wouldn't be a flawed system if ministers took notice of the legal advice. They just seem to override the advice for their own political ends."