Ruben Studdard (right) beat Clay Aiken in the American Idol final

The book, to be called I Don't Mean To be Rude, But... will hit the shelves in the US in December.

It is set to provide an insider's view of being a plain-talking judge on the US version of Pop Idol, which has been a huge hit on US TV.

Cowell - who is notoriously harsh with the show's would-be pop stars - will also use the book to give tips on how to make it big in music.

Cowell recently started the dating show Cupid on US TV

The deal was finalised about a week ago - just after Cowell agreed with US network Fox to return for the third series of American Idol.

The Fox deal also allows Cowell to develop new projects under his own newly formed production outfit, Simcow Ltd.

Last week, the production company's new TV dating series Cupid began on US network CBS, but pulled in disappointing ratings.

I Don't Mean To be Rude But... will be co-authored by Cowell's older brother, Tony, who is a journalist.

It will also recall Simon Cowell's 25-year career as a manager and executive in the recording industry.