Coffee expose Black Gold riled multinationals in the US and is now raising awareness in the UK. Chris Evans speaks to film-makers Marc and Nick Francis about taking on the world's second-largest export industry.

Following Super Size Me, An Inconvenient Truth and most recently Michael Moore's Sicko, brothers Marc and Nick Francis hope their documentary Black Gold, about exploitation in the coffee industry, will sway government policy on trade relations.

Though not on the same budget level as Moore's work, Black Gold certainly packs a punch. Pitting one man, Tadesse Meskela, who represents thousands of underpaid Ethiopian coffee farmers, against the multi-nationals and government trade bodies of the Western world, the film has sparked a huge debate in the US where it was released theatrically by California Newsreel last year.

'When we heard the story that these coffee farmers were struggling to survive in Ethiopia, known for producing some of the best coffee in the industry, we thought we have to look into it,' explains Nick, who lived in Ethiopia 10 years ago and witnessed the situation first hand. 'We asked ourselves, 'How can the coffee industry be worth $80bn, while the coffee farmers are getting poorer and poorer'''

Following Meskela on his journey from Ethiopia to find the right price for his coffee in London and Seattle, the brothers took in some interesting extremes. 'One month we were in the depths of the coffee fields of Ethiopia where people don't have shoes, the next we were in the US where people were competing to be the best coffee maker in the world.'

During filming, the major coffee sellers (Starbucks, Nestle, Sarah Lee, Procter & Gamble) were given the opportunity to provide their point of view, but they refused, says Nick. It was only after the Sundance premiere last year that Starbucks called Black Gold 'inaccurate' and 'incomplete'.

'When the film opened in LA, they urged all their customers to feel good about drinking Starbucks coffee. This is despite the fact the film is not about Starbucks,' says Nick. 'However, it tempted the other multinationals to see the film and now there are huge debates among consumers on sites like MySpace, which can only be a good thing.'

As first-time film-makers, the Francis brothers produced the film under their Speak-it label, and explored every avenue to find the $800,000 financing. 'We had support from the Sundance Institute, and took advantage of their Labs,' says Nick. 'The Channel 4 British Documentary Film Foundation also provided backing, as did the UK Film Council's Screen South. Then we had various trusts, foundations and international organisations, including the UN, provide in-kind support.'

The film will be released on June 30 in the UK by Dogwoof Pictures on 30 screens. The film-makers have been building a word-of-mouth campaign, particularly through their website, Marc says: 'The internet has propelled the existence of the film to an audience who otherwise wouldn't have found out about it.'

Looking to the future, the brothers have not ruled out fiction work but for now they are planning their next documentary, about China's expansion and its impact on Africa.