Investigative journalist Glenn Greenwald is to publish a book about Edward Snowden's exposure of mass public surveillance by the US government.

The book, which is due to be published in March, will contain new revelations about the NSA surveillance programs, according to publisher Metropolitan Books.

It was bought by editor Sara Bershtel, who has a track record of publishing outspoken non-fiction writers with special insights into Washington's corridors of power. So far, no deal has been announced for UK publication.