Cannes 2013: Lesbian love story Blue is the Warmest Colour emerges as surprise Palme d'Or favourite

French actress Lea Seydoux kisses fellow actress Adele Exarchopoulos as they arrive for the screening of the film 'Blue is the Warmest Colour' (La Vie d'Adele - Chapitre 1 & 2) in Cannes 2013 (Getty Images)

A three-hour long film containing explicit lesbian sex scenes has emerged as the surprise favourite for the Palme d'Or prize after winning rave reviews following its screening at the Cannes Film Festival 2013 last night.

Blue is the Warmest Colour (La Vie d'Adele - Chapitre 1 & 2) is the bookmakers’ favourite to take the coveted prize - despite industry fears that its graphic content and length will potentially hamper the film’s widespread distribution and commercial prospects.

Directed by Tunisian-born French director Abdellatif Kechiche, Blue is the Warmest Colour has been one of the most talked-about features of the French film festival which draws to a close this weekend.

It is about 15-year-old Adele and her lover Emma, played by relative newcomer Adele Exarchopoulos and Mission Impossible 4's Lea Seydoux.  It is a tale of awakening sexuality that is loosely based on a 2010 graphic novel of the same name.

There have been suggestions that the sex scenes are real, something fuelled by Seydoux who revealed last night that “what you see on screen is what we really did”.

The film is characterised by close-up shots of the faces -in particular the mouth- of the lead actress, creating a sense of intimacy and drama.

A critic from The Times described Blue is the Warmest Colour as "one of the most beautifully and unobtrusively observed love stories I've seen on film.”

While The Hollywood Reporter described it as: “Sure to raise eyebrows with its show-stopping scenes of non-simulated female copulation, the film is actually much more than that: it's a passionate, poignantly handled love story."

Kechiche told journalists at a Cannes press conference that he had not intended to make a film about gay rights.

Blue is the Warmest Colour is the latest film to add to the gay marriage debate, following the premiere of Steven Soderbergh’s Liberace biopic Behind The Candelabra starring Michael Douglas and Matt Damon at Cannes earlier this week.