The World Health Organization was urged Friday to examine its links to big drug firms after criticism led by Brazil and India over the fight against counterfeit drugs.

The two countries claim that major drug makers are unfairly labelling generic medicines as counterfeits, and using laws against patent infringements to suppress competitors who are making lawful generic drugs.

Member states of the WHO approved a resolution after four days of heated debate which calls on the world body to reassess its ties to the pharmaceutical firms.

"I am happy to inform you of the fact that... we have managed to reach an agreement," said Iran, which chaired marathon negotiations between member states.

The resolution called on the WHO to create a working group to work on combating counterfeit medicines.

It also called on the agency to examine its links with a partnership created in 2006 called IMPACT -- International Medical Products Anti-Counterfeiting Taskforce.

Among members of IMPACT is the International Federation of Pharmaceutical and Manufacturers' Association which represents drug makers, a point of contention for countries such as Brazil and India.

"That's what counts -- a check by member states on the policies of the WHO," said Brazil, which was among countries which questioned the role of IMPACT.

For Thiru Balasubramaniam, a health expert at the NGO Knowledge Ecology International, the intense debate this week was a "signal that many developing countries have lost confidence in IMPACT and WHO" on the issue of counterfeits.