The director told a Cannes audience the Bush administration wanted to keep the film off screens in the run-up to November's US election. The film examines the Iraq war and alleges connections between the Bush and Bin Laden families. Fahrenheit 9/11 is to get its world premiere in Cannes on Monday. Film studio Disney had backed out of a deal to distribute the film in the US for political reasons, Moore says. He has given no evidence to substantiate his allegations, but said "someone connected to the White House" and a "top Republican" had put pressure on film companies not to release the film. Moore said the few who had seen the film had told him "the potential for this film to have an impact on the election was much larger than they thought". Undercover in Iraq: The film was originally scheduled to be released through Disney-backed independent studio Miramax, before Disney blocked it. It is now expected to be released through a third party. Disney accused Moore of engineering a dispute about the film's release to gain maximum publicity. It said it had blocked the film because it wanted to be impartial during the election, but strongly denied coming under any outside pressure. The director has already shown the film at test screenings in the Midwest of the US. "The reaction was overwhelming," he said. "People who were on the fence - undecided voters - suddenly weren't on the fence." No-one from the White House was available to comment on his remarks. Moore has also revealed that he had three undercover film crews embedded with US troops in Iraq. "I was able to sneak three different freelance crews into Iraq," he said on Saturday. The soldiers had "expressed disillusionment that they had been lied to", said Moore. The film from Iraq was a "very important" part of the documentary, he added. "It is certainly something the Bush administration does not want people to see," said Moore.

Last year's Cannes was widely proclaimed as one of the dullest in festival history, with a paucity of stars, controversy and films to set the movie world alight. But this year, there are signs the annual bonanza on the French Riviera could return to form. A-list stars should be in abundance, with Brad Pitt, Cameron Diaz and Tom Hanks among those with films in the official selection.  Cannes will be a launch pad for Greek epic Troy, in which Pitt plays Achilles, while Shrek 2 - using the voice of Diaz - and The Ladykillers, starring Hanks, are both in the running for the festival's top prize, the Palme d'Or.  But the most attention could be given not to a screen idol but to the outspoken documentary-maker Michael Moore, whose new film, Fahrenheit 911, is also among the 18 movies in competition.  "Already, the entire world is going to be watching Cannes because of Michael Moore," according to Steven Gaydos, executive editor of Variety magazine and co-author of Cannes: 50 Years of Sun, Sex and Celluloid.  "It's the most anticipated film of the year now. So I think Cannes is going to benefit from that," he told BBC News Online. The buzz generated at Cannes could make or break the 46 movies that will get their world premieres at the event. 

Thousands of film-makers, executives and journalists will be on the look-out for the next Crouching Tiger or Pulp Fiction - a movie that emerges from the pack and goes on to become a classic.  One contender is Zhang Yimou's martial arts romance House of Flying Daggers, according to Mr Gaydos.  "No-one has seen the movie so nobody really knows what it is but there's a lot of expectation," he adds. Even if there is not a new Pulp Fiction, its director, Quentin Tarantino, will be heading this year's jury, and will ultimately decide who wins the festival's big prizes.  "His presence there will be magnetic," Mr Gaydos says. "Lots of stars, big controversy, a celebrated festival president - it all sounds good to me." And Cannes' artistic director Thierry Fremaux has put genre films like martial arts flicks, horrors and animations - not usually considered "serious" - on a par with the weighty arthouse offerings, Mr Gaydos says.  Mr Fremaux, in his first year solely in charge, has had the job of picking the best films from the 3,562 that were submitted - up more than 1,000 on last year.  The chosen films, which will be shown during the festival fortnight, are "as varied as imaginable", he has said.  "There is nothing to compare between them, if nothing other than a very strong direction resulting in strong stylistic differences." Last year's choices suffered from a hangover from the end of Mr Fremaux's predecessor's reign, according to Nick James, editor of Sight and Sound magazine.  "It was an atrocious selection last year," Mr James says. "But I'm optimistic that this year is going to be very exciting - I think it feels like a really vibrant mix." The festival is trying to be more "welcoming" to Americans after some US reviewers had a "paranoid edge" last year, he says. And there are more new film-makers on this year's list. "Most of the list is usually made up of auteurs who have been around a very long time.  "It feels a lot more flexible this year. And there does also seem to be a rather pronounced disinterest in British films." The only UK films in this year's selection are Dear Frankie, in the Un Certain Regard section, and three shorts in the Cinefondation - or film school - section. But Nick James adds: "For me, it's bound to be better than last year. I love Cannes - I'm somebody who has a good time every year, even when the films are bad." -Ian Young.