YouTube is the advertising model of the future, according to one of the world's biggest ad agencies. 

The viral, interactive and community-led nature of the free video-sharing site make it the ideal platform for ads and marketing, said Mark Tutssel, worldwide chief creative officer at the Leo Burnett ad agency. 

Tutssel, whose agency's clients include Samsung and General Motors, also highlighted the finding that YouTube has a greater reach among some US audiences than music broadcaster MTV. 

Speaking at the Cannes Lions 2006 advertising festival, Tutssel told the Financial Times that advertisers should use, and learn from, sites like YouTube. 

"Marketers must learn to let go of the control they think they have over their brand," he said. "Once consumers have interacted with brands, they will not go back to being shouted at by marketers."

Consumers should be allowed to create their own commercials, according to Tutssel, and make comments on other brands, even if they are negative.

Paul Kemp-Robertson, editor-in-chief at marketing industry magazine Contagious, backed up Tutssel's comments in an interview with the FT.

"On sites like YouTube, advertising can be an acceptable part of the landscape, sitting alongside music or films," he said. 

Tutssel's speech followed the awarding of the festival's Grand Prix to a campaign designed to look like a homemade internet video. Graffiti artist Mark Ecko was apparently shown defacing Air Force One, the US president's jet.

The advert claims to have reached 135 million people via the internet and subsequent free press coverage.