To delighted chants of “Knuuut, Knuuut” from children wearing Knut T-shirts, and the enthralled gasps of cameramen from around the world, the polar bear cub that has kept Germany cooing for months stumbled into public view yesterday.

Unperturbed by the presence of hundreds of journalists and seemingly unfazed by the life-or-death debate he has sparked, the tubby white bear with black button eyes padded around, took a dip in a pond at Berlin Zoo and bit his keeper on the backside.

The debut of the cub, reared by hand since his mother Tosca rejected him after he was born in December, was broadcast live in Germany and around the world.

He never strayed far from his keeper, Thomas Dörflein, who has been caring for him, even sleeping in his cage. After two hours he was taken back inside to applause, and as the satellite trucks rumbled off past startled elephants, children crowded around a stall selling toy Knuts. Weather permitting, the cub will go on show for two hours each morning from now on, zoo officials said.

Ragnar Köhne, the zoo’s curator, said that he expected 10,000 visitors today, twice the usual number. “I’ve never seen an event this big here,” he said. “It’s good because it’s raising public awareness of the plight of polar bears in the wild.”

Knut’s appearance threatens to upstage celebrations marking the 50th anniversary of the European Union in Berlin. Knut-mania is sweeping Germany in the biggest outpouring of public emotion since the World Cup. A song dedicated to him, Knut ist gut, is released on March 28 and newspapers and television stations have been tracking his progress anxiously, from his first few weeks in an incubator.

The coverage intensified this week after an animal rights campaigner said that hand-rearing polar bears violated animal rights and German media interpreted his comments as a call for Knut to be put down. The zoo swiftly assured an outraged public that Knut was in no danger.

Marine, 11, a schoolgirl from Berlin wearing a Knut T-shirt and clutching a Knut stuffed bear, said: “He’s so cute, I was shocked when I heard they wanted to kill him. We love Knut, I don’t know who came up with that stupid idea. He’s got to stay in Berlin.”

Konrad Schwanz, a tourist from Hamburg, said: “He’s like a cuddly toy. I’ve never seen anything so sweet.”

Dr Köhne said that, even though Knut has become something of a Berlin mascot, the zoo was unlikely to keep him. “We already have male and female polar bears for breeding purposes and we don’t need another male; other zoos need one. We have to think of animal management and of the animals themselves.”

Sigmar Gabriel, the Environment Minister, said : “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.”

Knut, who seemed more like a puppy than a bear as he licked Mr Dörflein’s hands, enjoyed having his tummy tickled and fought his way out of a blanket, is unlikely to remain cuddly for much longer.

“In a year or 18 months we won’t be able to go near him any more,” said Dr Köhne.

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