A new trade agreement designed to make medicine cheaper by relaxing patent laws was being implemented too slowly, Oxfam and Aids groups said on Tuesday
Oxfam, a British-based anti-poverty charity, also said that rich nations had taken little or no action towards meeting their obligations under the "Doha Declaration", leaving millions without affordable drugs.
Steve Cockburn, the Stop Aids campaign co-ordinator, said: "At the time, the Doha Declaration seemed like a great breakthrough for people in poor countries who urgently needed affordable treatment.
"Sadly, promising words have not translated into life-saving treatments."
The agreement, signed five years ago, was designed to put patients before profits and allow local pharmaceutical manufacturers to provide cheaper medicine for patients in developing countries.
Health activists say that access to cheap generic drugs is vital if poor countries are going to put up an effective fight against fatal diseases such as Aids and malaria.
In 2001 the World Trade Organisation granted a special exemption to allowing countries to put public health ahead of patents within its Trade Related Aspects of Intellectual Property Rights (TRIPS) agreement.
But Oxfam said that rich countries, particularly the US, were bullying developing countries to impose stricter patent rules in order to preserve pharmaceutical monopolies.
The clash over patents in the developing world has focused attention on a two high-profile cases including a dispute over the cancer drug Glivec, made by Switzerland's Novartis.
An Indian court in January rejected its patent application for Glivec, but Novartis is fighting back, arguing that the principle of intellectual property protection must be protected if innovation is to flourish.
The ruling has minimal commercial significance because 99 per cent of Indian patients are entitled to receive the drug free of charge under a Novartis compassionate use programme.
But Paul Herrling, the company's head of corporate research, told the Reuters Health Summit last week that India risked falling behind China in drug research if it did not shore up its weak patent protection system.