The senior Foreign Office lawyer who resigned after ministers ignored her advice that the war in Iraq was illegal has issued a damning legal critique of the occupation, claiming that the alleged abuse of prisoners "could amount to war crimes".
In her first newspaper interview since her resignation, Elizabeth Wilmshurst, the former deputy legal adviser to the Foreign Office, said that the basis for going to war should always be based on "facts" rather than an "assertion" about an "imminent threat". Ms Wilmshurst said "it could be alleged that the use of force in Iraq was aggression" while "the kinds of abusive treatment of Iraqi prisoners that have been alleged could amount to war crimes".
Her comments came as Sir Jeremy Greenstock, Britain's former envoy to Iraq, made the clearest admission yet that intelligence that Saddam Hussein had stockpiles of chemical and biological weapons was wrong. He said: "We were wrong on the stockpiles, we were right about the intention."
Ms Wilmshurst expressed concern about the size of the US civilian presence in Iraq. She also said she was worried about the lack of legal protection for Iraqis if they were harmed by allied troops or civilian contractors, including private security guards. She said it was "worrying" that the occupying powers had given immunity to US and British civilians which was "very, very wide" and "not what you would expect". They would be protected from prosecution even if they seriously injured Iraqi women and children.
She said the Bush administration's "war on terror" was legal "nonsense" - conferring no more powers on the US to detain prisoners than "the war against obesity" - and President Bush's policy of pre-emptive self-defence was illegal under international law.
Ms Wilmshurst, who is now head of the international law programme at the think-tank Chatham House, also raised questions about the powers of detention the Americans have in Iraq and Guantanamo Bay. She said it violated the Geneva Conventions to deny inmates in Guantanamo Bay a formal assessment of their status.
Although she said she would not discuss the advice she gave to ministers, she is understood to have told them that British participation in the invasion of Iraq would flout international law. She said there were deep concerns among international lawyers about the implications of the war on terror, which may be used as an excuse to hold prisoners indefinitely. "This rather extraordinary war against terror, which is a phrase that all lawyers hate ... is not really a 'war', a conflict against terror, any more than the war against obesity means that you can detain people," she said.
In a further side-swipe at American foreign policy she said President Bush's policy of pre-emptive self-defence, which would allow the US to invade any country it thought was a threat, was illegal under international law. "What people are worried about is just assertions that there is an imminent threat," she said.
The Butler inquiry report into intelligence on Iraq is to be published on 14 July, and reports suggest it will be critical of the intelligence services.
Sir Jeremy said on BBC's Breakfast with Frost: "There is no doubt that the stockpiles that we feared might be there are not there. We didn't know they were there, but we thought that there was a considerable danger that they were there, because the intelligence, not just in the American and British systems but in the French, German and Russian systems, also was quite compelling at the time." He said Washington was influenced by the Iraqi exile Ahmed Chalabi and underestimated the potential problems of post-war security.