The United States is to call for new measures to make it easier for poor countries to get hold of cheap anti-Aids drugs.

In a proposal, due to be lodged at the World Trade Organisation (WTO) on Tuesday, it will call for patenting rules to be relaxed when a country faces a public health crisis.

In a deal struck at the WTO's Doha summit last year, poor countries were given permission to make their own, cheap versions of patented Aids treatments, rather than having to buy the Western-produced originals which are out of their price range.

The new proposal would go further.

It would allow countries which do not have a drugs industry of their own to arrange for a third country to produce the cheap drugs for them.

Support

In practice this would benefit small countries such as Malawi or Zambia which have a grave Aids epidemic but do not have the capacity to produce their own, generic versions of the western-patented drugs.

Countries like India produce cheap Aids drugs

Under the new plan, the smaller countries could issue a licence to a country such as Brazil or India, which have a large pharmaceuticals industry producing cheap drugs.

According to Health Action International, only 10 out of 130 developing nations are currently able to manufacture their own drugs, meaning the vast majority do not benefit from the deal struck in Doha.

The US believes it will win broad support for its proposal which will be discussed at three days of talks on the Trade Related Intellectual Property Rights agreement (TRIPS) which controls the use of drugs patents.

"This initiative is part of the administration's global effort to address the serious health problems, such as HIV/Aids, afflicting African and other poor developing countries," said the US Trade Representative's office.

The European Union has announced it will also put forward a similar proposal at the meeting.

However, it may be more difficult to find agreement on how the new arrangements should work in practice.