Thailand has locked horns with pharmaceutical companies over so-called compulsory licenses, which temporarily suspend patent protections and allow production of cheaper generic drugs.

Activists at a three-day meeting in Bangkok hailed the government's efforts, saying the kingdom was leading the way in providing medical care to those who cannot afford expensive drugs.

"We are all looking to Thailand as a beacon that has shown us the way forward for a sustainable way to make medicines available and affordable," said Robert Weissman, a director of Washington-based Essential Action.

Pharmaceutical companies have derided Thailand's campaign as an infringement on their intellectual property rights, warning that lost profits would make it harder to finance research for medical innovations.

The companies have also complained that Thailand should have first consulted them before issuing the compulsory licenses, under the rules of World Trade Organisation.

Brook Baker, a professor of law at Northeastern University in Boston, insisted Thailand faced no such legal requirement.

"Under international law, it's completely lawful for Thailand to do what it has done," Baker told a press conference.

Other developing countries, notably Brazil, have also begun following Thailand's path in issuing compulsory licenses.

"The experience in Thailand was very inspiring for Brazil," said Carlos Passareli, spokesman for the country's Ministry of Public Health.