Leading academics and health professionals hoped to provoke debate on the need for a new international law to prevent falsified and substandard drugs reaching the market with a paper published in the British Medical Journal on Wednesday.

Their article, which sets out a clear case for a fake drugs treaty similar to existing ones on money laundering and human trafficking, comes a week before 100 states hold the first meeting of its kind to discuss the problem in Buenos Aires.

But lead author Amir Attaran of the University of Ottawa said he was told on Monday by the World Health Organisation (WHO) that he and other non-governmental representatives could not attend, following an objection by India.

A WHO spokeswoman declined to comment on the details of particular invitations but said it was up to member states to determine who was permitted to attend. Indian officials, whose government is wary of multinational drug firms using the issue to curb competition, were not immediately available for comment.

Attaran called it a scandal that only government officials would be at the meeting in Argentina to discuss strategy.

The clash exposes distrust among governments, the pharmaceutical industry and healthcare campaigners about how to tackle fake and dangerous medicines, which are a growing problem in both poor countries and rich. Risks include ineffective material packaged as medication and real drugs made in poor conditions.

In developing countries, the WHO estimates that more than 10 percent of medicine may be fake or substandard, with bogus malaria drugs a particular threat in parts of Asia and Africa.

But the danger is real in the rich world, too.

Earlier this year, fake vials of Roche's cancer drug Avastin were found in the United States, while a recent U.S. meningitis outbreak, due to contaminated steroid injections, shows the country is not immune to quality problems.

In the European Union, medicines are now the top illicit product seized at the border and authorities have found fake versions of drugs purporting to come from companies including Sanofi, Eli Lilly and AstraZeneca.

LAW TOUGHER ON TOBACCO THAN FAKE DRUGS

The need for action seems clear enough - but advancing the debate involves navigating some big divides.

India, whose large drugs industry produces cheap generic versions, is concerned that Western governments backed by Big Pharma are using the fight against fakes as a cover to restrict trade in unpatented medicines much needed by the world's poor.

Some health activists support New Delhi's charge that worries about counterfeit drugs are being hijacked by Big Pharma global pharmaceutical companies to protect their profits and patented products against legitimate generic competitors.

In east Africa, for example, international drug companies have taken advantage of anti-counterfeiting laws that are sometimes poorly drafted to curb sales of otherwise legitimate generics, threatening the availability of essential drugs.

India is particularly resistant to any role for pharmaceutical firms in setting the agenda, and Brazil has expressed similar concerns in the past.

Given the distrust, the authors of the paper in the BMJ - who include leaders of nursing, pharmacy and public health bodies - argue there is a need to find neutral ground to address what appears to be a gaping hole in international law.

They point out that thanks to a new convention on tobacco control, international law is now tougher on counterfeit cigarettes than it is on fake medicines.

We hope that this will form the basis for getting some consensus on a definition of counterfeit drugs, which would then be transferable into a legal instrument, said another of the paper's authors, Martin McKee of the London School of Hygiene and Tropical Medicine.