Bangalore, Oct 5 (IANS) A four-year-old Royal Bengal tiger died early Tuesday at the Bannerghatta National Park on the outskirts of this Karnataka capital, taking to three the toll of the big cats succumbing to salmonella infection in the zoo, a senior official said.

"The four-year-old tiger Minchu died this morning due to kidney failure though it was recovering from the typhoid causing bacteria. It seems to have succumbed to toxic remnants in the kidney," zoo assistant director B.C. Chittiappa told IANS.

Minchu was kept in isolation to prevent its infection from spreading to other 41 tigers, including 15 of them under treatment for the dreaded bacteria in the zoo, about 20 km from the city centre.

"Though Minchu was administered anti-biotic injections during treatment, we presume it was genetically pre-disposed to the bacteria, as its elder sister Divya too succumbed to the infection Sep 12," Chittiappa said.

Besides Minchu and Divya, a Siberian cross-breed, an unnamed 45-day cub died Sep 18 in the zoo due to the same infection.

Three other tigers also died in the zoo during the past one month due to old age.

The autopsy reports confirmed that the deaths were due to infection of salmonella bacteria that causes typhoid in human beings. Contaminated water and food are the source of the infection.

"As a precautionary measure, the 15 infected tigers are still kept in isolation though they have fully recovered from the infectious attack," Chittiappa said.

The tragic death of tigers prompted the central government to seek a report from the zoo authorities and the state government.

A team from the state-run Institute of Animal Health and Veterinarian Biologicals is investigating the deaths of tigers in the zoo, a major tourist attraction.

The over three decades old park, spread over 20,000 acres and surrounded by dense forest and scrub land, houses 1,300 carnivorous and herbivorous animals.

About 1,300 kg of meat, largely beef, is supplied to the zoo to feed the animals daily.

The park also has crocodile farm, a butterfly enclosure and a snake park.