An official tiger census estimates the number of animals in the wild at around 3,700, but critics say that is over twice the true figure. Over 30 years since the threat to tigers was first recognised, with the foundation of Project Tiger by then prime minister Indira Gandhi, they claim tiger numbers are no higher now than they were then, at around 1,800.

"We are at the same stage as we were in 1972, when Project Tiger began, " said Neel Gogate, of WWF, formerly the World Wildlife Fund. "We are even behind that, because human population pressures have gone up manyfold."

Conservationist Valmik Thapar, who presented the BBC's Land of the Tiger series, has condemned Project Tiger for "poor management, corruption, lack of funding and outdated scientific methods".

The alarm was sounded last year when the government was forced to admit that 122 tigers had been killed by poachers between 1999 and 2003.

At the same time it emerged that despite an official population of 28, no tiger had been seen in Sariska National Park in Rajasthan since October 2004. They are presumed to have fallen prey to poachers, who can earn up to $50,000 for a single carcass for use in traditional Chinese medicine.

At Kanha National Park in the central Indian state of Madhya Pradesh, tourists pay 600 rupees ( 11) a time to view tigers from elephant-back.

Queues of up to 30 vehicles can form to see one cat.

The local field director of Project Tiger, K Nayak, insists the official population of 136 tigers in Kanha is accurate, but critics say the counting method amounts to little more than guesswork. Nayak was less certain about poaching.

"I can't say it is completely under control, but I can say our tigers are more safe than previously, " he said.

But the prices paid for tiger parts must be an irresistible lure to impoverished villagers who have been moved out of a 1,000 square-kilometre area of the park, and he believed the answer to poaching was to give them different incentives.

"People will conserve the tiger if they get something out of the tiger, " said Nayak, who wants a tax on the hoteliers who benefit from the tourists who visit Kanha.

? Sankha Guha presents Spirit of the Tiger on BBC Radio 4 at 9pm tomorrow, 10 April