Germany's best-loved and biggest animal star, the polar bear Knut born in captivity in Berlin Zoo, has died aged four, his keeper announced Saturday.

Heiner Klös, the keeper, found the four-year-old's body floating in the water of the pool in his enclosure.

Klös said that between 600 and 700 visitors to the zoo witnessed the polar bear's death.

It was unclear exactly how he died. An autopsy will be carried out to determine the cause of death.

At the age of 4 years and 3 months, Knut is a relatively young polar bear.

He has been outlived by his mother Tosca, with whom Knut has been sharing an enclosure since last autumn, when Knut's partner Gianna was sent back to her home zoo in Munich.

"Knutmania" swept Germany, and the world, after his birth on December 5, 2006, when zookeeper Thomas Dörflein had to feed and look after Knut – the first polar cub born in captivity at the Berlin Zoo in more than 30 years - after his mother rejected him and his twin brother, who later died.

Attendance at the zoo rocketed, and he even appeared on the cover of Vanity Fair magazine.

Interest waned as Knut got older and bigger, and lost the cute factor.

Knut's place as Germany's best-known exotic animal was nearly eclipsed last year, when Paul the Octopus, kept at a marine world museum, correctly predicted a succession of World Cup matches.

Autor: Natalia Dannenberg (dpa, AP, AFP)
Editor: Andreas Illmer