Koen Mortier's directorial debut Ex Drummer has already been dubbed the "Flemish Trainspotting" ahead of its world premiere in Rotterdam's Tiger competition at the end of this month. An adaptation of the novel by Herman Brusselmans, the 'bad boy' of Belgian literature, Ex Drummer is an expletive-laden, low-life yarn about a battle of the bands, full of graphic sex and violence. Headlines should accompany its local release, also in late January.

Mortier made Ex Drummer through Brussels-based production company Cccp, owned by commercials house Czar.Be, which Mortier set up as an affiliate company of Amsterdam-based Czar.NL in 1998. When he is not working on features, Mortier has a lucrative career directing advertisements for the likes of Deutsche Bank and Nike.

"Herman is a really controversial writer. I'm the fourth director who has tried to make a film out of his work. I wouldn't say he's an anarchist, but he's totally rude," the 41-year-old film-maker says of the novelist who inspired his movie. Like others who have tried to tackle Brusselmans' work on screen, among them Frank Van Passel and Jan Bucquoy, Mortier faced a struggle to find backers. "They (the public funders) thought Ex Drummer was too low class to make a film out of," he says. "They want to make films based on the cultural side of Flanders, and culture for them is intellectual."

"It was not easy to get the film financed," agrees producer Eurydice Gysel. In the end, much of the $1m budget came from Czar and sister commercials companies Mercurio in Italy and Quad in France. Only when the film was shot did the Flemish Film Fund (VAF) agree to invest in post-production.

Despite its troubled gestation, the film - which will screen in the market in Berlin after festival outings in Rotterdam and Gothenburg - is stirring up interest internationally. A-Film has picked up Benelux distribution rights. The producers hope shortly to announce a sales agent.

The film has its share of grotesque moments - severed penises, scenes of domestic violence - but it is more subtle than its shock tactics might suggest. Certain sequences are elaborately shot, using slow motion and reverse footage. The director was trying to address the problem of racism in Flemish society. "My characters are mad and racist. I try to put racism in my characters as proof of how stupid you have to be to be racist."

Mortier has two projects in development: Blink Of A Second - about a security guard racked with guilt over his failure to intervene when someone blows himself up in a shopping centre - and serial-killer drama Killroy, which Mortier hopes to shoot in the US.

In the meantime, he will continue making commercials. "In Flanders, it's the only way to survive as a film-maker."

Ex Drummer (2006) adapted by Mortier from Herman Brusselmans' novel
10 Jaar Leuven Kort (2004) short-film compilation
A Hard Day's Work (1997) short, also wrote
Ana Temnei (1995) short, also wrote.