Colombia's government proudly claims that it is the biggest producer of biodiesel and ethanol in Latin America after Brazil, but human rights groups do not share that enthusiasm.

Critics warn that the cultivation of palm trees to produce biodiesel is a threat to Colombia's indigenous groups and other minorities, including Afro-Colombians.

In rural areas, there is evidence that some people have been forcibly displaced to make way for biofuel production.

Last year, the United Nations stopped its investment in the sector in Colombia.

But while ethanol production in Brazil has been pored over by experts and activists, the challenges faced by Colombia remain relatively unexamined.

complete article: news.bbc.co.uk/2/hi/business/8084735.stm