IN EARLY December last year, a shock Radio 4 newsflash announced that the chemicals giant Dow was finally accepting full responsibility for the Union Carbide disaster that devastated Bhopal in 1984.

When a cheery spokesman claimed the company was offering a $12bn settlement to the surviving victims, the news rocketed across the globe in minutes. Only hours later did Dow manage to deny the story. The BBC, the world media and the Bhopal survivors themselves had been cruelly hoaxed.

For many, it was a prank too far by Mike Bonanno and Andy Bichlbaum, aka The Yes Men, who have spent years turning media terrorism into performance art. The duo now admit they felt "guilty as hell" after the hoax backfired, but they still arguably achieved their goal. Dow’s intransigence and the festering injustice of Bhopal were back in the headlines.

In fairness, Bonanno and Bichlbaum have pulled off many more successful stunts over the years, usually victimless and frequently hilarious. A new documentary, called The Yes Men, records some of their greatest hits.

Among them are spoof news interviews in the guise of World Trade Organisation spokesmen, a lecture to high-school students in which a bogus McDonald’s delegation suggest feeding recycled human faeces to Third World customers, and a bizarre presentation to a Finnish textiles conference which ends with Bichlbaum demonstrating how to oppress workers from inside an inflatable gold phallus. It’s hard-hitting satire with a surreal twist, Chris Morris meets Michael Moore.

"Some people jump off cliffs with parachutes," says Bonanno. "We get a similar adrenaline rush from this activity. As far as fulfilling our political goals, in some ways it works and in some ways it doesn’t. But it opens up a lot of questions, and we are going to keep trying to find that fulfilment that might come from political change."

Since meeting in the mid-1990s through shared involvement in anti-globalisation causes, The Yes Men have been playing pranks on the New World Order for almost a decade.

"Most people are willing to go along with authority, and that’s very frightening," says Bichlbaum. "Of course, when we were delivering the McDonald’s lecture, suggesting that the poor would eat recycled post-consumer waste, the students began to realise halfway through the lecture. This is what we expected from every one of the lectures and we were surprised to find that didn’t happen. But the students knew."

Besides one-off attacks on politicians and corporations, the duo’s chief target is the World Trade Organisation. Behind all the joking, this is their serious agenda. "We’re saying tear down the WTO, build up something else that is about creating better conditions for people and the environment," Bonanno says. "OK, that is not something we can all do, but we can all work towards it."

By now the WTO is wise to The Yes Men’s tactics. Official spokespeople were initially hostile, but have now taken the smart public relations step of cautiously complimenting the duo for raising topical issues. Their real aim, Bichlbaum says, is to undermine dissent by co-opting and neutralising them.

"We’re nobodies, we have no power," he says. "The only power we can get is what they give us by attacking us. So at a certain point it seemed like they got a bit smarter about that. In a way, the WTO are learning from this and from the thousands of activist groups around the world that criticise them. They are having to scramble a lot to change their public face."

The Yes Men became a film project after the duo contacted documentary directors Dan Ollman, Chris Smith and Sarah Price three years ago. Bonanno and Bichlbaum were fresh from giving a bogus WTO speech to an Austrian conference about selling votes to the highest bidder. They had planned an escape route, expecting to be ejected from the building. Instead, their outlandish ideas were applauded, so they hit upon the notion of recording their next stunt on video.

"When they told me they had done this speech and nothing happened, it was just mind-blowing," says Smith. "Then they said, ‘We’re going to Finland to do this other lecture on textiles of the future, and this time we’re definitely going to get found out because we’re pushing it so far’. We couldn’t resist."

A former assistant to Michael Moore, who briefly appears in The Yes Men, Smith previously directed the documentaries American Job and American Movie. These are fertile times for non-fiction films with a radical bent, Smith says. His political education came from "working for Michael and reading, because you don’t get it from the news in America. You get it from the internet and from books."

While most documentary makers at least pay lip service to journalistic impartiality, the trio behind The Yes Men are shamelessly partisan. "We’re an arm of The Yes Men, I guess you could say," Ollman says. "But basically we thought our job was to just document what was happening, document their actions in the conferences. You can definitely say there are two sides to every story, but this documents the side of our protagonists and their journey."

The common ground between activists and film-makers is their shared use of cheap technology, low-cost travel and the internet as weapons of mass subversion. "Production costs can be so cheap now with digital technology," says Smith. "We own the cameras from a couple of years back, from when we were doing an internet television station, and we had the editing equipment. So basically the cost of making a movie is a $13 tape and a plane ticket."

As for Bonanno and Bichlbaum, they are now full-time activists, existing on a perilous income of film profits and arts grants. After the Bhopal debacle, where will they strike next? "Look in the news," says Bonanno. "We don’t know... well, we do know, but we can’t say."

The Yes Men is on general release from February 18