Damon to replace DiCaprio in spy film

Matt Damon

Bourne Identity star Matt Damon has signed on to replace fellow heart-throb Leonardo DiCaprio in Robert De Niro's new spy film The Good Shepherd.

Oscar-winner Damon, 34, is taking over from Titanic megastar DiCaprio in the $US110 million project that tells the story of the US Central Intelligence Agency through the eyes of an agent, Daily Variety said.

It is unclear why DiCaprio left the project in which he was due to co-star.

De Niro is directing, producing and co-starring in the film that is due to begin production in March.

It is loosely based on the life of famed CIA Cold War spook James Jesus Angleton and tells the story of James Wilson, played by Damon and De Niro at different stages of the character's life, who is recruited to become a founding member of the American spy agency, and follows him through his 40-year career.