‘‘After taking approval from the (Health) ministry, we have written to all the states to stop the veterinary use of diclofenac. The state drugs controllers have three months to phase out the drug,’’ Dr Ashwini Kumar, Drug Controller General of India, said.

Prime Minister Manmohan Singh had, in March last year, asked the ministries to phase out the drug in six months.

‘‘It has been decided that licences granted to manufacture diclofenac formulations for veterinary use should be withdrawn and safer drug like Meloxicam...be permitted to be used...You are requested to implement the decision and to ensure its phasing out,’’ said the Centre’s directive to states.

Welcoming the move, conservationists, however, pointed out that a gazette notification to this effect must be issued as soon as possible. ‘‘It’s a very positive decision but the government must also formally ban diclofenac so that people can take anyone manufacturing or using the drug to court,’’ said Dr Asad Rahmani, director of the Bombay Natural History Society.

Kumar admitted that he could not issue a notification due to ‘‘legal limitations’’. Under Section 26 A of the Drugs and Cosmetics Act, 1940, a veterinary drug can only be banned if it harms the animal it is administered to or has any secondary effect on human beings.

When cattle die during treatment with diclofenac, the chemical remains in their visceral organs and causes kidney failure and renal gout in vultures when they feed on these carcasses.

‘‘It’s a unique case. But we believe our advisory unambiguously conveys the government’s decision...We have a deadline and we will check the progress. If necessary, we can always take the legal route,’’ he said.

Conservationist Mike Pandey, whose film The Vanishing Vultures garnered widespread public support, stressed on effective implementation: ‘‘Finally, there is hope but we have to ensure that this ban doesn’t become...like the ban on plastic. We must give those resilient birds a chance to recover.’’