Sandra Bullock

Sandra Bullock

Sandra Bullock and George Clooney's 'Gravity' will open the 70th annual Venice Film Festival.

The new space-set 3D blockbuster directed by Alfonso Cuaron will receive its world premiere at the prestigious film gala in Venice, Italy, on August 28, festival organisers have confirmed.

The film sees the Oscar-winning stars play deep space astronauts who find themselves drifting aimlessly in orbit when a seemingly routine space walk goes wrong.

Bullock will play extraordinary medical engineer Dr. Ryan Stone who is on her first space shuttle mission, while Clooney stars as veteran astronaut Matt Kowalsky, who is teamed with her.

The sci-fi film was co-written, produced and directed by Cuaron, who penned the screenplay with his son Jonas.

The ambitious Warner Bros. flick - which has no supporting cast - was filmed in England on a budget of $80 million.

'Iron Man 3' star Robert Downey Jr. was originally linked to play Kowalsky but dropped out of the role due to his commitment to another project and was replaced by 'The Descendants' actor.

Bullock won her role after 'Black Swan' actress Natalie Portman passed on the movie, while others considered for the character included Blake Lively and Scarlett Johansson.

The film will receive its worldwide release in October.

Last year's Venice Film Festival was opened by Mira Nair's 'The Reluctant Fundamentalist'.