But one official, who asked not to be named, scoffed at explanations offered so far to the Indian media that the female bear may have tried to tunnel her way to freedom.

The zoo official said the bear may have been poached or died from carelessness.

An unidentified keeper told the Indian Express the bear -- weighing between 90 to 110 kilograms (198 to 242 pounds) -- had been missing since February 22.

A couple of days later, two keepers found a tunnel which they believed had been dug by the bear possibly to escape from an enclosure surrounded by a water-filled moat, he said.

Two men were immediately sent into the tunnel to look for the animal but they gave up for fear of attack, the report said.

On March 3, zoo authorities tried to smoke the bear out but failed, leading them to think it had died underground. A digger was being called in to check.

But the zoo official who spoke to AFP said black bears do not tunnel.

The bile of the black bear -- found in the lower reaches of the Himalayan Mountains -- is used in Chinese traditional medicine and believed to cure rheumatism.

Experts say there were an estimated 5,000 to 7,000 bears in the wild.

"A bear of that size housed in a moated enclosure filled with water just cannot simply disappear," the zoo official said.

"And Himalayan black bears are not diggers like the sloth bears. These are excuses to cover up the real story of what happened to the bear. But unfortunately, we may never know."

Recently two jaguar cubs died in the zoo after consuming disinfectant left lying around by some careless keepers, he added.

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