A group of experts calling for a global treaty to stop the lethal trade in fake medicines has been barred from attending a WHO meeting, highlighting deep divisions that are blocking progress on the subject.

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 yesterday.

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 by the WHO that he and other non-governmental representatives could not attend, following an objection by India.

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 per cent of medicine may be fake or substandard, with bogus malaria drugs a particular threat in parts of Asia and Africa.