WASHINGTON, USA (AP) — The Pentagon's top lawyer has informed the former Navy SEAL who wrote a forthcoming book describing details of the raid that killed Osama bin Laden that he violated agreements to not divulge military secrets and that as a result the Pentagon is considering taking legal action against him.

The general counsel of the Defence Department, Jeh Johnson, wrote in a letter transmitted yesterday to the author that he had signed two nondisclosure agreements with the Navy in 2007 that obliged him to "never divulge" classified information.

"This commitment remains in force even after you left the active duty Navy," Johnson wrote. He said the author, Matt Bissonnette, left active duty "on or about April 20, 2012," which was nearly one year after the May 2011 raid.

By signing the agreements, Bissonnette acknowledged his awareness, Johnson wrote, that "disclosure of classified information constitutes a violation of federal criminal law." He said it also obliged the author to submit his manuscript for a security review by the government before it was published. The Pentagon has said the manuscript was not submitted for review, although it obtained a copy last week.

Johnson said that after reviewing a copy of the book, "No Easy Day," the Pentagon concluded that the author is in "material breach and violation" of the agreements, implying that it contains classified information. He did not, however, say explicitly that the book reveals secrets.

Pentagon press secretary George Little declined today to say whether the book contains classified information.

Rep Peter King, chairman of the House Homeland Security Committee, said in a statement today that all who are entrusted with classified information are obliged to protect it.

"Whether it is administration officials or special forces operators, national security leaks are wrong and should be prosecuted to the fullest extent possible," King said.

The book is to be published next week by Penguin Group (USA)'s Dutton imprint. The Associated Press purchased a copy Tuesday.

Johnson addressed his letter to Mr "Mark Owen," using quotation marks to signify that that this is the author's pseudonym. His real name is Matt Bissonnette.

Bissonnette referred requests for comment about the letter to his publisher, which was not immediately available.

"I write to formally advise you of your material breach and violation of your agreements, and to inform you that the department is considering pursuing against you, and all those acting in concert with you, all remedies legally available to us in light of this situation," Johnson wrote.

The Pentagon has not revealed how it got a copy of the book.