George Clooney kicks off the 2011 Venice film festival on Wednesday with the world premiere of his political drama The Ides of March, setting the tone for a star-studded 11 days on the Lido waterfront.

The 50-year-old Hollywood heavyweight acts in and directs the movie based on Beau Willimon's play Farragut North, and appearing alongside him is Ryan Gosling as an idealistic young press secretary to Clooney's governor Mike Morris.

The evening red carpet screening marks the opening of the August 31-September 10 event, which promises eagerly awaited movies and A-list stars who will hope the high-profile launch puts them in the frame for awards next year.

Thousands of journalists and fans are descending on the Lido island across the water from Venice to catch a glimpse of their idols and bring the glamour of the world's oldest film festival to a global audience.

The roll call of celebrities expected this year includes Clooney, Colin Firth, Keira Knightley, Matthew McConaughey, Kate Winslet, Matt Damon, Jude Law, Gwyneth Paltrow and pop superstar Madonna.

It marks a significant turnaround for director Marco Mueller, who was criticized last year for a low-key festival and faces growing competition from the annual rival event in Toronto which overlaps with Venice.

It is a program that tells you how much support we get from the artists, the film makers ... and it proves that Venice really stands as a major platform to create a special kind of visibility, Mueller told Reuters.

Among the most hotly anticipated titles is Tinker, Tailor, Soldier, Spy, an adaptation of John Le Carre's spy novel starring recent Oscar winner Colin Firth and Gary Oldman.

Other standout titles in competition include Briton Andrea Arnold's take on the Emily Bronte novel Wuthering Heights, U.S. director Ami Canaan Mann's Texas Killing Fields and William Friedkin's Killer Joe.

In A Dangerous Method, Canadian David Cronenberg explores the rivalry between Carl Jung and Sigmund Freud as a young woman (Knightley) comes between them.

Roman Polanski worked on the screenplay for his latest movie Carnage, featuring Winslet, Jodie Foster and Christoph Waltz, while under house arrest in Switzerland last year.

The 78-year-old was eventually freed after the Swiss authorities decided not to extradite him to the United States, where he is still wanted for sentencing for having sex with a 13-year-old girl in 1977 in Los Angeles.

Acclaimed Russian director Alexander Sokurov brings Faust and Hong Kong's Johnnie To presents Life Without Principle, a story touching on the economic crisis and its effect on ordinary people.

Outside the main lineup, Madonna makes her second foray into feature films with W.E., a drama loosely based on divorcee Wallis Simpson whose relationship with Britain's King Edward VIII led to his abdication in 1936.

Egyptian documentary Tahrir 2011 covers the revolution and overthrow of the old regime, Philippe Faucon explores radical Islam in La Desintegration and Al Pacino plays himself and King Herod in Wilde Salome.

Steven Soderbergh promises an all-star cast including Damon, Winslet, Marion Cotillard, Law and Paltrow in Contagion, about a lethal airborne virus that spreads panic.