Tony Blair’s former defence secretary Geoff Hoon has claimed he was told to burn a memo from the attorney general that cast doubt on the legality of the Iraq war. In revelations that critics say cast further doubt on the decision to award the former prime minister a knighthood, Hoon recalled in extracts from his recently published memoir that Blair’s chief of staff had instructed him to burn the document. Hoon wrote in his memoir, See How They Run, that he had had been under pressure from Mike Boyce, the chief of defence staff, to provide him with clear legal direction that his forces could take action in Iraq, in lieu of a UN resolution authorising force, the Daily Mail reported. He claims to have received a copy of complex advice from the then attorney general, Lord Goldsmith, which was “very long and very detailed legal opinion”. He wrote: “I was sent a copy from Downing St under conditions of considerable secrecy. I was told that it was for my eyes only and that I should not discuss its contents with anyone else. I had no idea who else had received a copy.” Hoon said the advice was “not an easy read” and concluded that the Iraq invasion would be lawful only if the prime minister believed that it was in the UK’s national interest to do so. “It was not exactly the ringing endorsement that the chief of the defence staff was looking for, and in any event, I was not strictly allowed to show it to him or even discuss it with him,” he wrote. “Moreover, when my principal private secretary, Peter Watkins, called Jonathan Powell in Downing St and asked what he should now do with the document, he was told in no uncertain terms that he should ‘burn it’.” Hoon said the document was not burned. “I agreed that we should lock the document securely into an MoD safe to which only he had access. For all I know it is probably still there.” Powell told the Daily Mail he had not ordered the advice to be burned and described it as a separate “minute” that he had asked Hoon to destroy on Goldsmith’s request. In his memoir, Hoon also describes the humiliation of being sacked as defence secretary two years later, saying Blair phoned him to tell him the news rather than meet face-to-face. More than 700,000 people have now signed a petition to rescind Blair’s knighthood, awarded by the Queen in the new year honours list. But the decision to award him the honour was defended by the Labour leader, Keir Starmer, who said on Tuesday it was “not a thorny issue” to give the award to someone who had served a long term as prime minister. “I understand there are strong views on the Iraq war. There were back at the time and there still are, but that does not detract from the fact that Tony Blair was a very successful prime minister of this country and made a huge difference to the lives of millions of people in this country,” Starmer said.