According to eyewitnesses, Mr Nordin, who was seen shouting and flinging items about shortly before the incident, vaulted a low wall and landed in a moat in the enclosure, four metres below.

Carrying a yellow pail and a broom, he then crossed the 1.75m-deep moat, walked up to a rocky ledge near where the animals were and began agitating them by swinging the broom.

As two of the tigers approached him, he covered his head with the pail, lay down on the ground, and curled himself into a foetal position, two eyewitnesses, an Australian couple, told police. Their identities were withheld pending investigations.

In a flash, two of the extremely rare white tigers were on him. One took a swipe at him with its paw – which is about the size of a softball glove – and he began screaming in pain, said another eyewitness, Dutch tourist W. R. de Boer.

He said many in the crowd of 30 or so onlookers at the enclosure initially thought the intrusion was part of a show.

But when Mr Nordin began screaming, they reacted with horror.

‘Some were screaming: ‘Go away’ to the tigers and others were shouting to scare the tigers,’ he said.

The cries alerted zoo staff, and the alarm was raised.

About 20 keepers arrived within minutes. Some tried to prevent the attack from continuing by throwing brooms and dustbin covers, while the rest ushered the shocked onlookers away.

Also deployed were two zookeepers armed with rifles and live ammunition, but these were not used, said the zoo’s assistant director of zoology, Mr Biswajit Guha.

Despite the efforts of the keepers, one tiger continued attacking Mr Nordin for several minutes, the zoo said in a statement yesterday.

It only relented after a door to the tigers’ feeding area was opened. The animals retreated to it, leaving the cleaner motionless on the ground.

Once the tigers were in the feeding area, the door separating it from the rest of the enclosure was closed, and keepers were able to reach the cleaner.

It was too late, however. Mr Nordin, who hails from Sarawak, had been bitten on the neck and suffered a fractured skull. He died before police arrived.

His colleagues later told zoo staff that the contract worker, who had been working at the zoo for about 41/2 months, had been behaving strangely minutes before the incident.

He had thrown his cutters and meal coupons about before telling them in Malay: ‘Goodbye, you won’t be seeing me again.’

He then rode off on his bicycle.

The Australian tourists also said they saw him shouting and throwing some things as he walked by the crocodile exhibit, just 10 minutes from the tiger enclosure.

Yesterday’s incident was the first time a person had been killed by an animal at the zoo since it opened in 1973.

Before this, the most serious incident occurred in 2001, when Chawang, a bull elephant, gored his keeper of 18 years, Mr Gopal Krishnan.

The keeper suffered fractured ribs and a punctured lung, and was in hospital for close to two months before he eventually recovered.

The zoo, which had to stop the tram ride and prevent visitors from entering during the incident, said yesterday that it would close the white tiger exhibit temporarily as a precautionary measure. It did not say how long the closure would last.

It has closed the exhibit for the moment, but this is to facilitate investigations into the incident rather than for safety reasons, it said.

A moat separates the tigers from the visitors’ bridge by 8.5m at the nearest point, and by 10m at the furthest.

The centre of the moat, its deepest portion, is 1.75m deep, while water on either side comes up to 1.5m. The fences on the sides of the enclosure are 5.8m high, and those at the back, 4.7m high.

Another 1.5m-high hot-wire fence stands in front of the 4.7m fence as an additional precaution.

These measurements ‘conform to international safety guidelines imposed by the Association of Zoos and Aquariums’, said Mr Biswajit Guha, the zoo’s assistant director of zoology.

He pointed out that regular safety audits are held, with the last done on Sept 11. Only minor defects, such as rust on the fences and overgrown vegetation, were found, and rectified.