Combo shows Knut the polar bear cub playing with a blanket during his first public appearance in the Berlin Zoo, March 23, 2007. [AP]

The three-and-a-half-month old white cub padded gingerly round his new enclosure to the gasps and sighs of onlookers.

Fortified by a breakfast of porridge, the puppy-sized cub sniffed the grass and rolled in the dust before delighting the crowds by splashing in a pond.

"I want to take him home," said Daniel Wolff, five, whose mother had bought him a specially made "Knut" cuddly polar bear toy on sale on a stand outside the enclosure.

Knut stole the heart of Berliners after he was born in December but rejected by his mother Tosca. A bearded zookeeper moved into the enclosure to look after him round the clock.

But Knut's fate grabbed global attention after an animal rights campaigner said hand-rearing polar bears was a violation of animal rights. German media interpreted his comments as a call for Knut to be put to sleep.

"We are not worried about Knut's future," Berlin Zoo vet Andre Schuele told reporters. "As a male he will grow big and strong. Polar bears are loners and he will be fine -- it doesn't matter that he has been hand-reared."

At least 200 journalists from around the globe gathered at the zoo for "Knut Day," and his outing threatened to overshadow the start of a major EU summit taking place in the capital at the weekend, zoo official Ragnar Kuehne said.

"There is always something special about bringing up a baby polar bear on a bottle and with Knut, the added fear that he might die bolstered solidarity for the bear," said Kuehne.

Cameramen from Japan, the United States, Brazil and Finland jostled on ladders to take the best pictures. German television channels covered Knut's first public steps live and some newspaper journalists had to post live podcasts of the occasion.

Knut has also drawn attention to the plight of polar bears as worries grow that global warming is contributing to the melting of their habitat.

German Environment Minister Sigmar Gabriel has adopted Knut and used his appearance to further the debate on climate change.

"Knut is in safe hands here but worldwide polar bears are in danger and if Knut can help the cause, then that is a good thing," said the minister as he accompanied Knut on his walk and tickled his chin for the cameras.