As the countdown began on Saturday to the Cannes film festival's Palme d'Or prize ceremony, jury president Sean Penn said his panel should "do just the opposite" of the Oscars and crown a groundbreaking, unconventional film.

"The best way to be honest is to try to emancipate ourselves from the effects of fashion, to try to find what will stay with us forever," he said in an interview with French daily Le Monde.

"We've got to do the opposite of the Academy that gives out the Oscars, where manipulation and very good marketing are rewarded," said the 47-year-old US actor leading the nine-strong jury who will decide the winning entry on Sunday.

Penn, who won an Oscar for best actor in 2004 for his performance in Clint Eastwood's drama 'Mystic River', said it had been a very good year for films at Cannes.

He only regretted that "there weren't a few more comedies in competition" — a wry reference to the predominantly dark fare at the 61st edition of the festival.

The event kicked off last week with 'Blindness', a Brazilian film with an apocalyptic vision of the future, and followed up with 'Waltz With Bashir', an animated documentary centred on Israel's role in a Beirut refugee camp massacre.

Since then, the 22 films in competition for the Palme d'Or have included an Argentinian movie set in a women's prison, a gritty Italian movie on the mafia, and Clint Eastwood's 'Exchange', about a mother whose son is abducted.

With politically-minded Penn heading the jury, the bets are out that it will favour messages over pure fiction.

'Waltz With Bashir' would fit that category, as would Steven Soderbergh's four-hour epic on the life and times of Latin American revolutionary Ernesto "Che" Guevara.

Penn told Le Monde that the political content of each of the entries was open to debate.

"You would be surprised to see to what extent questions of a political nature are raised by each of the jury members relating to films or elements of films that on the surface do not appear to have them," he said.

"But in general we focused on the cinematic experience. A principle that, of course, can be interpreted in many different ways."

He said he had asked the jury members not to read reviews of the films, which might colour their judgment.

Penn said at the start of the festival that the devastating earthquake in China and the cyclone in Myanmar would cast a shadow over the event.

The jury includes Italian actor and director Sergio Castellitto, Hollywood actress Natalie Portman, Mexican director Alfonso Cuaron, Thai filmmaker Apichatpong Weerasethakul, German actress Alexandra Maria Lara, French directors Rachid Bouchareb and Marjane Satrapi, and French actress Jeanne Balibar.

AFP