A deal which could give some of the world's poorest countries access to cheap drugs has edged closer.
The deal could see rules on drug patents relaxed
According to the World Trade Organisation, the United States, Brazil, India, South Africa and Kenya have struck a deal.
These countries had been at loggerheads over plans to make cheap medicines more widely available.
The proposals, which have yet to be published, are now set to be put to the rest of the WTO's 146 members.
If backed, the deal could see millions of people around the world being given access to cheap drugs to treat malaria, Aids, tuberculosis and other serious diseases for the first time.
The principle of allowing developing countries access to cheap versions of key drugs had been agreed at WTO talks almost two years ago.
Many of these drugs are patented, which means they cannot be copied for 20 years.
The WTO talks were aimed at easing these rules for some medicines.
This would enable countries in need to import cheaper versions of essential drugs.
Officials from the United States and key developing countries have been in talks for months trying to resolve the issue.
But on Wednesday, Vanu Gopala Menon, the WTO's chief mediator on this issue, declared that agreement had been reached.
"The five are agreed," he told journalists.
Mr Menon said he planned shortly to table a document for consideration by all the remaining 141 WTO member nations.
However, he warned that they will need time to examine the deal.
The United States blocked a deal on cheap drugs last December even though it was backed by all other members of the WTO.
US negotiators said the deal would allow too many drugs patents to be ignored.
They said the proposed deal would mean that illnesses that are not infectious, such as diabetes and asthma, could also be treated with cheap, generic drugs.
It is understood that the US will lifts its opposition to a deal if WTO states pledge not to abuse the system and to only waive patents "in good faith" and not for commercial gain.
They will also be expected to take all reasonable steps to ensure cheap versions of drugs do not make their way onto markets in rich countries.
South Africa's top trade envoy Faizel Ismail said the plan
was "reasonably balanced" and "close to an acceptable solution".
"It provides some comfort to the US pharmaceutical
companies that were worried about abuse," he said.
The issue has been casting a long shadow over global free trade talks since their launch in 2001.
Trade ministers will discuss the deal at the next WTO meeting in Cancun, Mexico, in September.
British MPs warned that poorer countries will need to improve their health services if the deal is to have an impact.
Jenny Tonge, a member of the Liberal Democrats, said: "It is absolutely essential that richer countries and the aid agencies help provide proper health delivery systems to ensure that these drugs are taken properly.
"If they are not, resistant strains of bacteria and viruses will develop and render them useless.
"For HIV/AIDS, good nutrition and proper medical supervision is essential and drugs alone will not solve the problem."