US defence officials move to block spy book

Anthony Shaffer worked for the Defense Intelligence Agency, and defence officials believe his book reveals classified information.

The book, Operation Dark Heart: Spycraft and Special Ops on the Frontlines of Afghanistan, was due to be released on 31 August.

It is understood more than 9,000 copies have already been printed.

The New York Times said Department of Defense officials were in negotiations to buy and destroy all the copies of the book.

But the DoD told the BBC that while they had been "working closely and co-operatively with the publisher and author", it was premature to say what might happen.

The Army Reserve, with whom Shaffer was a lieutenant-colonel, apparently cleared the book for publication, but the DoD says a proper security review has not been done.

Review copies of the book are already in circulation and the New York Times said it had been able to buy one online. Amazon's entry describes the book as "temporarily out of stock".

The material concerning the DoD is understood to include names of US intelligence officers and details of National Security Agency eavesdropping activities.

Publishers St Martin's Press say the book's release date has been postponed until 24 September.