By Emma Jane Kirby BBC Geneva correspondent

US pharmaceutical giant Pharmacia has unveiled plans to expand access to much needed medicines to treat HIV/Aids in the world's poorest countries.

It has developed a joint project with a Dutch non-profit-making group, the International Dispensary Association (IDA), to allow generic drug manufacturers to sell cheaper versions of its Aids drug, Rescriptor.

The scheme could make copies of Rescriptor available to patients in 78 developing countries, Pharmacia said in a statement issued at the World Economic Forum in Davos, Switzerland.

Pharmacia also said it would also take steps to ensure the cheap drugs did not leak from African markets back into the European Union.

'Practical'

With more than 42 million people worldwide now diagnosed as HIV positive, the majority of whom have no access to treatment, Pharmacia said the time for action had come.

Under the plan, the company said it would transfer the manufacturing technology of Rescriptor, its sole Aids medicine, to IDA.

IDA will then select various pharmaceutical companies to make the drug - and they, in turn, will agree to supply it to patients in developing countries.

The out-licensing deal "provides a very practical way in which profit levels in wealthy countries are maintained [and] intellectual property is guarded", said Pharmacia spokesman Dr Michael Friedman.

At the same time, large quantities of badly needed drugs are made available to poor countries "at reasonable price, and with assured quality", he added.

The World Trade Organisation has been drawing up a draft plan to let developing countries override patent laws and import cheap generic drugs.

However, those negotiations ground to a halt in December 2002 when the United States rejected the proposal.

Pharmacia said its new scheme was a positive contribution to ensuring that everyone, however poor, can get access to life-saving medicines.