From ALLAN HALL in Berlin

Last updated at 23:49 02 March 2008

A year ago, he was a cute and cuddly ball of white fur who captured the hearts of millions worldwide.

But Knut the polar bear has grown up fast - as this startled young visitor to Berlin Zoo discovered.

Knut now weighs 22 stone and has six-inch claws and a fearsome set of fangs to match.

And he seemed to be particularly keen to test them on the three-year-old boy lying on the ground next to his enclosure.

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Fangs for the memories: Knut is separated from this little boy by six inches of glass

Fortunately for the youngster, six inches of glass capable of withstanding a mortar attack separated him from the jaws of the world's most famous captive bear.

Knut was rejected by his mother at birth in December 2006.

Some animal rights activists said it would be better for him to die than to be weaned by mankind.

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Harmless: Knut when he hit the headlines as a cute cub

The zoo directors decided to let him live, however, and he went on to become a major attraction, pulling in £5million in revenue in a year.

But his days of being picked up and cuddled are long gone.

He is, after all, a wild animal and now not even the keeper who raised him by hand dares to get close.