Christian Aid partners have launched a petition supporting the Brazilian government's decision to bypass the patent on an Aids drug produced by the US pharmaceutical giant, Merck.

Brazil has followed Thailand's lead in importing a much cheaper generic version of the drug Efavirenz after negotiations with Merck over a price reduction broke down.

Merck offered to price the pills at £0.56 which represents a thirty per cent discount. But Brazil argued it should be able to pay the same amount as Thailand which pays £0.33.

The country will now be importing an Indian-made version of the drug for £0.23.

This represents a significant saving in a country where 180,000 people are HIV positive and 70,000 are using the anti-retroviral drug, Efavirenz.

Brazilian president, Luiz Inacio Lula da Silva, said: "From an ethical point of view the price difference is grotesque. From a political point of view it represents a lack of respect, as though a sick Brazilian is inferior."

Under World Trade Organisation agreements, countries are allowed to issue 'compulsory licences' for generic drugs in cases where public health is at stake. The company which developed the drug still receives a marginal royalty, but it is much less than it would get for selling its branded version.

Merck argues that such licences risks stifling innovation in a field where new drugs are needed all the time.

Christina Pimenta, from the coalition that launched the petition supporting the government, claimed that most of the research for new drugs was carried out with public money and Merck's threat was therefore misleading.