A book about the US raid that killed Osama bin Laden by a former Navy Seal, who participated in the mission, contains classified information and the Pentagon is reviewing legal options, a Defence Department spokesman said.

Mark is a hero who has written a book that celebrates his teammates and the Seals and when people get a chance to read this book they will agree- co-author

But the book’s co-author denied it contained any information that would jeopardise the safety or future missions of Navy special forces personnel.

The book, No Easy Day, chronicles last year’s stealth operation in which members of US Navy Seal Team Six swooped by helicopter into the al-Qaeda leader’s house in Pakistan and killed him, ending an intense decade-long manhunt that began with the September 11, 2001, attacks on New York and Washington DC.

The successful operation gave President Barack Obama a national security victory that he is touting in his bid for re-election against Republican rival Mitt Romney.

It is still unclear whether the government ultimately will pursue criminal charges against the book’s author, Matt Bissonnette, who was part of a team considered national heroes for taking down Bin Laden.

The book, which went on sale on Tuesday, was written under the pseudonym Mark Owen.

It became the No. 1 bestseller at online retailer Amazon.com.

Pentagon spokesman George Little said it was a “no-brainer” that the book should have been submitted to the US government for pre-publication review. He said legal options were being reviewed, but would not comment on whether any actual steps would be taken.

“Sensitive and classified information is contained in the book,” Little said at a regular news briefing.

“When you have special operations units that perform these missions, there are tactics, techniques, and procedures, not to mention human life, that are in play,” he said.

“And it is the height of irresponsibility not to have this kind of material checked for the possible disclosure of classified information. We have very serious concerns after having reviewed the book.”

But Kevin Maurer, a veteran journalist who is Bissonnette’s co-author, insisted that the ex-Seal was very careful about what was included in the book.

“When we worked on this book Mark Owen was meticulous about adhering to his desire to never do anything to undermine the Seals’ mission or put his former colleagues in harm’s way,” Maurer said in a statement.

“I personally feel that Mark is a hero who has written a book that celebrates his teammates and the Seals and that when people get a chance to read this book, they will agree,” Maurer added.

Bissonnette’s lawyer previously questioned whether his client was legally bound to submit the book to authorities for pre-publication review, as the Pentagon says he was.

Despite its concerns about the contents of the book, the Pentagon is not preventing it from being sold at military outlets, Little said.