THE image from the film Syriana shows a bearded George Clooney in the street, a car ablaze in the background. It could be a scene from any of the blockbuster movies Hollywood churns out, the ones packed with big explosions and breathtaking stunts. Except this picture comes from a new breed of film - ones that aren't afraid to tackle world problems, especially American ones, in politically-motivated movies.

Clooney and others like him want to save the world, not from a mad villain but from itself. He and an increasing band of US film-makers want to bring about social change through movies.

Syriana tells how the CIA interferes in the running of an Arab country so the US can keep the petroleum rights. Far from being run out of town, Clooney and the film are being showered with praise. He won best supporting actor at this week's Golden Globes. An Oscar nomination seems a certainty.

Already Syriana and his other new film, Good Night And Good Luck, about journalist Edward R Murrow during the 1950s McCarthy Communist witch-hunt era, have brought issue and message movies to the fore.

They, along with sexual harassment drama North Country, have all come from Participant Productions, set up by billionaire eBay co-founder Jeff Skoll with the declared intent of producing political movies.

"Traditionally, people come to Hollywood for financial reasons or they think it's glamorous," he told Newsweek magazine. "I'm doing this because I believe that movies and documentaries can be a wonderful pathway to change the world."

No longer is documentary-maker Michael Moore a lone voice in criticising politicians and ridiculing their policies on film. There were boos when he collected his Academy Award for best documentary Fahrenheit 9/11 because he dared to question US involvement in the Middle East. His attitude was condemned as un-American.

The change has come about partly because enough time has passed since the tragedy of 9/11 and the launch of the President's war on terror for audiences to feel comfortable about questioning what's happened. Disillusionment with government policy over Iraq, the military's continuing presence and killing of US servicemen has added to the public's concerns and made them more open to receive critical comments, even in fictionalised movies.

This is all very different to the immediate aftermath of 9/11 when worried studios edited out shots of the World Trade Centre from movies for fear of offending audiences. Now several movies about the tragedy are in production. Director Oliver Stone is shooting one about two cops trapped in the Twin Towers, while British director Paul Greengrass is filming the story of Flight 93, the United plane that crashed in Pennsylvania.

The on-going national debate about involvement in Iraq and terrorism is moving into the cinema as film-makers attempt to reflect the mood of the nation, its doubt and dismay, on screen. It's reached the stage where Star Wars creator George Lucas was accused of turning last year's final episode, Revenge Of The Sith, into a political allegory for the Middle East situation.

Clooney knows that people have been afraid in the past to tackle politics, especially the Middle East and the war on terrorists, for fear of being labelled unpatriotic. "Big stars would come up to me and whisper that they supported me, I thought it was strange that they felt they had to whisper. But people seem to be less afraid now. They're calming down. Lots of people are starting to ask questions," he says.

Already we've had the Bafta-nominated drama The Constant Gardener, about pharmaceutical companies dumping unsafe drugs in the Third World, and Lord of War, with Nicolas Cage as a US arms dealer selling weapons to African dictators.

British director Sam Mendes's new film, Jarhead, is set during the first Gulf War. He says there was no government pressure on the studio not to make the film, but big pressure from society not to stick out your neck.

"That's been going on for a long time, a wholesale cultural and media opting out of discussion on the war," he says. "You see that suddenly breaking down with a movie like Jarhead, Munich or Syriana, or all these movies that are politically invested in the present day.

"When you do that, in America especially, you accept straight away that the movie is going to divide people because everyone has an opinion on the war. Very few people have opinions about King Kong, they just want to be entertained. Jarhead has divided people, which I've liked."

Steven Spielberg's film Munich tells of the covert hit squad taking revenge on those responsible for the killings at the 1972 Olympics. The story still has resonance today. "It's an event that sheds light on a lot of current events and it allows us to step back and ask what happened 33 years ago and what did we learn from it?," says producer Kathleen Kennedy.

One of the 100 richest people in the world with an estimated $3.5bn fortune, Jeff Skoll can afford the $100m of his own money that he's investing in films through Participant Productions. "It's a very inexpensive way to do a lot of good," says a man who's been called both a "social messiah" and "innovative philanthropist".

Participant's involvement doesn't end with the film's release. The debate continues and action is planned through its website participant.net. All three of its movies have inspired campaigns which the public is urged to support and get involved with.

Oil Change aims "to reduce our dependence on oil". Possible action includes joining a virtual march on Washington, donating to projects to create an oil change, and learning how to reduce your own dependence on oil.

The makers of Syriana did their bit for the cause as the first major motion picture to be "climate neutral" by offsetting 100 per cent of carbon dioxide emissions generated by the production during filming. They invested in renewable energy, such as wind and methane power, in projects that might not otherwise have happened.

Stand Up, springing from North Country, urges action to stop sexual harassment and sexual violence. Report It Now takes Good Night And Good Luck as the starting point for the public to compel the media to get back to reporting in the public interest.

It's all so much more organised than making an impromptu political speech at the Oscars ceremony or refusing to accept an award to highlight the plight of native American Indians.

The traditional movie cry of "Lights, Cameras, Action" has been replaced, to quote the headline in a US film magazine, "Lights, Cameras, Activism".

The Constant Gardener and Jarhead are showing in cinemas now. Munich opens on Friday, North Country on February 3, Good Night and Good Luck on February 17 and Syriana on March 3.