Goldmining has always been a dirty business. The Romans mined the metal by washing soil from Spanish hillsides, resulting in ecological disaster. Prospectors in the Californian gold rush of 1849 used mercury to remove gold from rock, polluting San Francisco Bay so badly that the city's residents are still advised not to eat too much local fish.

The technology has come on a bit since then and today's mining companies spend vast sums to limit the damage. But some mines are cleaner than others and Rio Tinto's Grasberg operation in West Papua, Indonesia, is infamous among environmental and human rights campaigners.

One of Rio's largest shareholders, the Norwegian Government, said yesterday that the company's continued 40 per cent ownership of this mine was unacceptable. The Norwegian Government Pension Fund has sold its £500 million stake in Rio because it did not want to risk contributing to “grossly unethical conduct”.

Rio is not responsible for the day-to-day operation of Grasberg, which is handled by the majority shareholder Freeport McMoRan. For years Freeport has faced accusations that it is polluting local rivers. It insists that no harm has been done, but the Norwegian Government disagrees.

Freeport has also been accused of contributing to human rights abuses by the Indonesian Army. Five years ago Freeport admitted that it had paid millions of dollars to the Indonesian Army for security. Research by the Australian Government has shown that the army was responsible for the disappearance of numerous people around the mine in the mid-1990s.

Freeport is not the only Rio Tinto partner to raise concern among environmentalists. Rio has a 19.9 per cent stake in Ivanhoe Mines, the Mongolian copper explorer. Ivanhoe is run by Robert Friedland, or Toxic Bob, as he is known to many environmentalists.

Mr Friedland was formerly the chairman of Galactic Resources, which owned the Summitville goldmine in Colorado.

Summitville was responsible for the worst cyanide spill in United States history when 85,000 gallons of contaminated water leaked from the mine in 1991. US taxpayers are still paying millions to clean up the site.

Perhaps Tom Albanese, the chief executive of Rio, should listen to the Norwegians and consider making additions to his $15 billion programme of asset sales.

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