The secretive Nobel Peace Prize committee has accused its former secretary of a breach of trust by revealing details about its proceedings in a book published last week.

The committee says that Geir Lundestad, who stepped down last year after 25 years as its non-voting secretary, had like other members signed a statement saying he understood that the vow of silence about the committee's discussions and decisions about the candidates and the award applied for 50 years.

In his book, Secretary of Peace, Lundestad wrote, among other things, that the 2009 award to President Barack Obama failed to live up to the panel's expectations.

The committee said in a written statement Monday that Lundestad had "broken several points of his vow of silence," but did not elaborate.

Lundestad declined comment.