diclofenac, the anti-inflammatory painkiller, is claimed to have devastated the population of the world's most common large bird of prey.

It was blamed when the oriental white-backed vulture started disappearing from the eastern landscape in the 1980s.The birds were found sick and dead across India and in neighbouring Pakistan and Nepal.

A study in 2004 claimed to have revealed why the birds were dying.

The RSPB said the veterinary drug was the main cause of vulture declines. The birds were eating the carcasses of animals that had previously been treated with the medicine.

They were then dying of kidney failure. It has been shown that even if less than 1% of animal carcasses contained lethal levels of the drug, this would have been enough to cause the collapse of vulture numbers.

Making diclofenac was outlawed in India in 2006.