Idi Amin, the evil Pumpkin King, Robert F. Kennedy and the youngest of three Aborigine wives... They will all be part of the 50th London Film Festival next month.

In the space of two weeks, the festival will screen 181 feature films and 131 shorts from over 50 countries around the world. Hollywood blockbusters will rub shoulders with independent gems shot on a shoestring in places like Uruguay, Iran and Bangladesh.

On 18 October, the capital's premier film event will open with The Last King of Scotland, the story of a young Scottish doctor who becomes the confidante of Ugandan dictator Idi Amin. "It has many of the qualities which we've looked for," LFF artistic director Sandra Hebron explained, "originality, energy, intelligence and wit. Put simply, it is a great story, well told."

Organisers chose this year's line-up from more than 2,000 films they watched throughout the year. With four world premieres, 32 European and 123 UK premiers, the resulting mix as rich and varied as the population of London itself.

Demi Moore resurrected

Fast Food Nation, an expose of America's junk food industry based on Eric Schlosser's bestselling book, stands alongside Bamako - a drama in which poor Africans put globalisation on trial.

In Venus, the elderly Peter O'Toole sparkles as a veteran actor who shows London's sites to his best friend's young niece - not with entirely pure motives. Kate Winslet is equally impressive in Little Children as a stifled Boston supermum who starts an affair with the local designer dad. And Demi Moore may just resurrect her career with her turn as an alcoholic nightclub singer in Bobby, Emillio Estevez's poignant account of the assassination of Robert F Kennedy.

From abroad, The Yacoubian Building - about corruption, homosexuality and Islamic fundamentalism in a Cairo apartment block - may repeat its sell-out run Egypt on British soil.

There are also quirkier experiments. Ten Canoes conveys the cautionary tales of an old Aborigine with three wives (one important, one jealous and one pretty) in anthropology- inspired black and white. The South African film Son of Man sets the life of Jesus in a violent township, where the Messiah preaches a hand-gun amnesty while Judas spies on him with a video camera.

Home-grown talent is on show in 37 Uses for a Dead Sheep - a warm-hearted take on the life of the semi-nomadic Kirghiz tribe in Asia - and Ghosts, an investigation into the Chinese cockle picker tragedy in Morecambe Bay.

David Lean's 1940s masterpieces Oliver Twist and Great Expectations were restored for the festival, while the 3D version of Tim Burton's iconic animation film The Nightmare Before Christmas will lead the family film line-up.

Burton will also be a guest on one of the onstage interviews, along with the Oscar-winning actor Dustin Hoffman. Paul Verhoeven, director of Basic Instinct and Total Recall, will lead a master class. More than 400 other filmmaking guests will attend the festival.

World's largest surprise screening

To mark the LFF's 50th anniversary, the specially commissioned film A Portrait of London will be screened free of charge in Trafalgar Square on Friday 27 October. Director Mike Figgis, of Leaving Las Vegas fame, led a group of London-based filmmakers to assemble this series of "visual postcards" reflecting the capital.

Two days later, the festival's traditional surprise film will be shown on no fewer than 50 screens across the capital - some in cinemas, others a recording studio, a hospital and even a prison. It will be the world's largest ever surprise screening, organisers said.

When the LFF was born five decades ago, its organisers wrote in the first programme of their vision for "a festival of the cream of festivals". Audiences at the great international film festivals were "largely restricted to members of the press and the film trade". But London would make the best of those selections accessible to "the ordinary, intelligent cinema-goer", they promised.

Fifty years on, the LFF is still a festival of festivals. But it also aims to be a platform for new talent in world cinema, Ms Hebron said. "In this significant year, we're very excited to be able to bring such a strong selection of original and distinctive films to London."

Fittingly, the clamour of film voices ends on November 2 with Babel - titled after the Biblical account of how sudden language differences scattered people across the world. Brad Pitt and Cate Blanchett star in this ambitious work interweaving four parallel stories. But in the end, it concludes that prejudice - rather than language barriers - is what truly divides us.