Rogue State: A Guide to the World's Only Superpower by William Blum had languished below 200,000 on Amazon's top-seller list but stormed to 21 yesterday, with the online retailer struggling to meet demand.

After issuing new threats to attack the US and calls for President George Bush to withdraw American troops from Iraq, Bin Laden then found time to "plug" Mr Blum's book. "If Bush decides to carry on with his lies and oppression, it would be useful for you to read the book Rogue State," he announced in his message relayed to a potential audience of billions via Arab satellite television.

Oprah Winfrey's book club has boosted the careers of many an author, but in Osama bin Laden she may have an unlikely new rival. A book by an obscure American historian has shot into US best-seller lists after the elusive leader of al-Qa'ida endorsed it in an audio message aired last week.

Mr Blum is a long-standing and fierce critic of the White House, laying scorn on Mr Bush and his predecessor, Bill Clinton. His 320-page book tears to pieces US foreign policy and its opening line reads: "Washington's war on terror is as doomed to failure as its war on drugs has been."

Mr Blum has described the attacks on 11 September as "an understandable retaliation against US foreign policy", stopping short of calling that ajustification.

Once an employee of the State Department until his career was cut short after he led demonstrations against the Vietnam War, Mr Blum, 72, has been taken aback by his sudden celebrity. News networks in the US are clamouring to interview him. "The Washington Post refuses to publish my letters, but now they are coming to my house," he told reporters.

Talking to a New York radio station, he said most interviewers have pressed him to reject Bin Laden's endorsement but he says he has no qualms about being promoted by the world's most wanted man. Mr Blum said: "I happen to share with Osama bin Laden a certain view of US foreign policy, and this is great if more people read my book."