Steven Spielberg has backed La Vie d'Adele to be a breakthrough racy hit after he and the Cannes jury named it the festival's top film.
French police say thieves raided the hotel room of a representative of Swiss jeweller Chopard and made off with jewels.
Baz Luhrmann's glittering adaptation of The Great Gatsby will open the Cannes Film Festival tonight.
A French assistant prosecutor has described an audacious jewel heist from a hotel in the French Riviera resort of Cannes which netted an estimated haul of £88m.
Philippe Vique told the Associated Press the suspect broke in through French doors at the hotel that open out onto Cannes' famed Croisette.
He then held up three private security guards, two vendors and a manager of a temporary jewellery exhibition with a handgun, then fled on foot.
Mr Vique said the hold-up itself took place in the space of about a minute.
"He took a bag containing a briefcase and a small box, and then fled by another French door on the inside. He left on foot ... it was very fast."
A French prosecutor has said the estimated value of diamond jewels stolen in Cannes at the Carlton Hotel has been raised to $136 million (£88m).
Police had previously said $53 million (£34m) was netted in Sunday's theft, which was one of biggest jewellery heists in recent years.
An armed robber targeted a temporary exhibition from a diamond house owned by Israeli billionaire Lev Leviev in the daring raid in broad daylight.
The armed robber at the Carlton Hotel in Cannes targeted a temporary jewellery exhibition it was hosting from a diamond house owned by Israeli billionaire Lev Leviev.
It remains unclear how many pieces were stolen.
The valuable jewels were due to be on public display until the end of August.
The Carlton Hotel, which has seen £34m worth of jewels stolen in broad daylight by an armed robber, earned its place in movie history for its association with jewellery theft.
The French Riviera resort provided the setting for Alfred Hitchcock's 1955 heist-thriller To Catch A Thief, which starred Cary Grant and Grace Kelly.
The Carlton built a close relationship with the film industry and now plays a central role in the annual Cannes Film Festival.
French police have said they are urgently hunting the armed man who today robbed the Carlton Hotel in Cannes of jewellery worth 40 million euros (£34 million) in broad daylight.
A Cannes police spokesman, quoted by the BBC, said: "A full and urgent operation is under way to catch the culprit and recover these jewels. Thieves see Cannes as rich pickings."
Today's daring jewels heist took place at the Carlton Hotel, located on the Croisette promenade, and one of the most prestigious locations to stay in France.
The hold-up, which took place in broad daylight, was reportedly the work of one armed man who is said to have made off with the jewels in a briefcase.
In May, during the city's famous Film Festival, jewels worth €777,000 (£650,000) were stolen from the Novotel hotel room an employee of Swiss jewellers Chopard.
An armed man has stolen jewels worth about 40 million euros from a hotel exhibition in the French Riviera resort of Cannes, the BBC has quoted French officials as saying.
La Vie D'Adele, a story about two young female lovers by French filmmaker Abdellatif Kechiche, has won the 2013 Palme d'Or, the top prize at the Cannes Film Festival.
White gowns dominated at the Cannes screening of Nebraska.
Heidi Klum, Nicole Kidman and Elsa Zylberstein all wore stunning pale floor length dresses.