Celebrity polar bear Knut dies

Germany is mourning the loss of the world's most famous polar bear Knut, who died at Berlin Zoo over the weekend.

The four-year-old collapsed in his enclosure on Saturday in front of 600 stunned onlookers.

Knut shot to fame when he was rejected by his mother and was hand-reared by a keeper at the zoo.

The bear became an instant star, appearing on the cover of Vanity Fair magazine and generating millions of pounds for the attraction through the sale of photographs, key chains and soft toys.

Berlin mayor Klaus Wowereit has described the news of Knut's death as "awful", adding that he was the "star of Berlin Zoo".

Knut's keeper Heiner Kloes said the bear was not sick and there is no indication of why he died.

Fans of the animal have been flocking to the zoo since news of his death was made public, leaving candles, photographs and red roses in tribute.