Natalie Portman will star in a biopic of former US first lady Jackie Kennedy that covers the four days after her husband's assassination, trade magazine Variety reported on Thursday.

The film, "Jackie", starts at the point when US president John F. Kennedy was shot dead in November 1963.

"" 'Jackie' talks about the days when Jackie Kennedy becomes an icon but has lost everything," Vincent Maraval, of production company Wild Bunch, told Variety.

The film is expected to set off a bidding war at Cannes as companies try to win rights to distribute it around the world.

Due to go into production later this year, "Jackie" is being directed by Chilean Pablo Larrain, who won wide acclaim for his film "No" about the advertising team that helped topple dictator Augusto Pinochet.

It is being produced by Darren Aronofsky, who directed Portman to an Oscar in the 2010 film "Black Swan".

Portman is also in Cannes this week, presenting her directorial debut, "A Tale of Love and Darkness".