A white tiger has killed a male student who witnesses say climbed over a fence at the New Delhi zoo in India and into the animal's enclosure.

National Zoological Park spokesman Riyaz Ahmed Khan said the man ignored repeated warnings that he should not get too close to the outdoor enclosure and climbed over a knee-high fence and small hedges.

Other eyewitnesses said the man was leaning over the barricade and may have fallen inside the closure by accident, according to IBN News Live.

He then jumped down into a protective moat, said Mr Khan. The tiger, which lives on a grassy tree-filled island, grabbed the man from the moat. Footage broadcast on NDTV showed the tiger carrying the man around the island.

Authorities eventually frightened the tiger into a small cage inside the enclosure. Police arrived on the scene "very quickly", but could not save his life.

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The man, whose body remained in the outdoor enclosure two hours after the attack, was dead by the time help reached him, Mr Khan said.

Deputy Commissioner of Police M.S. Randhawa identified the man only as Maqsood and said he was thought to be about 20 years old.

"The tiger was just being a tiger," said Belinda Wright, who has spent years working to protect India's dwindling numbers of wild tigers. "An unusual object fell into his domain. ... He's a wild animal in captivity. It is certainly not the tiger's fault."