Asian vultures may face extinction in India unless a farm drug responsible for their large-scale decimation is banned outright, according to a report Sunday ci ting researchers.

The population of the oriental white-backed vulture has declined by 99.9 percent and the numbers of two other highly-endangered species by 97 percent since 1992 in India, a story in the Hindu newspaper said citing a study in the Journal of the Bombay Natural History Society.

The study had not yet been released on the society's website and the authors were not immediately available for comment.

Conservationists say the vultures arc fast vanishing because of livestock painkiller diclofenac, which India banned in 2006 after it was found that the birds absorbed toxic amounts of the drug as they scavenged animal carcasses.

But despite the ban on the drug's manufacture, it is widely available, according to BirdLife International, a global partnership of conservation organisations, which also quoted the study in a post onits website.

"Time has almost run out to prevent the extinction of vultures in the wild in India. The ban on diclofenac manufacture was a good start but a ban on the sale of diclofenac and other drugs known to harm vultures is vital," said coauthor of the study Rhys Green.

"Efforts must be redoubled to remove diclofenac from the vultures' food supply and to protect and breed a viable population In captivity," lead author Vibhu Prakash was quoted as saying by the organisation.