Voicing the opinion that animals could be kept in captivity only for conservation purposes, animal rights activists are demanding that zoos, as entertainment centers, be abolished.

Already, the use of animals has been banned in circuses and last year, the Calcutta high court asked the Central Zoo Authority to take steps to improve conditions in zoos.

"We don't want zoos that are only for entertainment," said Debasish Chakraborty of the People for Animals, a leading animal rights group.

Indian zoo laws stipulate that animals should be kept in conditions as close to nature as possible. However, in most Indian zoos, wild animals are kept in crammed, dirty cages.

"Zoos can be replaced with rescue and rehabilitation centres," Chakraborty said.

Also see: CBI to probe Sariska tiger poaching

Officials of Compassionate Crusaders Trust, another animal rights group, claimed that authorities were violating zoo laws which stipulate that sick and weak animals shouldn't be kept for public display.

"Instead of wasting money on the present-day zoos, authorities should spend on building animal rescue and conservation centres," said a CCT official.

Animal rights activists say depletion of natural habitats meant that there was a need for keeping sick and endangered animals in 'human custody.'

"But the fact is, in a zoo, it's life imprisonment for the animals for the pleasure of the human race. It's subjugation of the weaker species," Chakraborty said.

India is already facing criticism from environmentalists for failing to protect tigers whose population has fallen from some 40,000 a century ago to just about 3,700 because of poaching.  Some environment groups put the number at less than 2,000.

Reports in March said the entire tiger population at the Sariska tiger reserve in western India had been killed by poachers. There were 16-18 tigers in Sariska a year ago.

Graphic: The missing tigers of Sariska