According to WWF, more than three hundred thousand tons of tainted coffee left Indonesia in 2005. It says coffee grown illegally inside the national park is being sold to local traders who mix it with legally grown beans before exporting it to countries like Japan, Italy and the US.

The report says several well-known brands are involved. One company, Nestle, issued a statement saying it regrets such unacceptable activities and never willingly purchases coffee from dubious sources. But, the company said, it's often difficult to determine the precise origin of its coffee.

The head of the park told the BBC that some sixty thousand hectares - around a fifth of the park's total area - had been taken over by illegal plantations, most of them producing coffee. The park, which covers three hundred thousand hectares, is policed by only sixty rangers, he said, and around fifty community workers. Stopping the expansion of the plantations is all but impossible. Instead, he said officials are trying to entice farmers to move outside the park and to raise public awareness of the problem.

The area is home to some sixty tigers and around the same number of rhinos. Both species are endangered and park officials say destruction of their natural habitat by farmers is making them easier targets for hunters.