Although the initial response from Roche was restrained, the company is now seeing one of its worst commercial nightmares coming true. Dozens of third world countries would like to be able to make their own versions of expensive, patented anti-AIDS drugs, but only a few have pharmaceutical industries with the ability to do it, and markets big enough to make the exercise worthwhile. Brazil, like India, is among only a handful of countries which pose a real threat to the drug companies' monopoly, and their profits.

Although the World Trade Organisation rules protect the drug companies' patents, they do allow some leeway to poor countries facing serious health emergencies.

Roche has given no indication yet of whether it would take Brazil to court, but the WTO rules are complicated and they're hedged around with conditions. A company spokesman said that the drug in question has a US patent, and so Brazil had an obligation to consult the United States. He said the company would now be checking exactly who had done what and why, before it decided on any further action.

ELIZABETH BLUNT, BBC, LONDON