By Marina Adami

BERLIN (Reuters) - The aging mother of Knut, the famous hand-reared polar bear who captured German hearts and the world's attention in his short life, was put down at Berlin Zoo on Tuesday because it said she was blind, deaf and suffering.

Tosca, who rejected her cub Knut at birth in 2006, was nearly 30 years old, the zoo said.

Knut, who died aged 4 in 2011 from an epileptic fit, became the zoo's star attraction after Tosca rejected him at birth. That would have normally meant death but the fluffy white cub was saved against the odds and reared by zookeeper Thomas Doerflein.

"Deaf, blind and disoriented, Tosca was found stumbling around in her cage on Monday," the zoo said in a statement.

"She lost her sense of smell. It was a pathetic sight. Veterinarians, animal protection officials and zoo officials came to a joint decision to put the elderly Tosca out of her misery."

Tosca was born in Canada but spent time in the Communist East German state circus for a while before the Berlin Wall fell. She had been at Berlin Zoo since 1998.

At the height of the Knut frenzy in 2007, thousands of visitors from around the world flocked to the zoo to see the rescued cub frolic in his enclosure.

Knut's survival inspired a dizzying array of merchandise. Other German zoos have tried to repeat Knut's fame by promoting other celebrity animals but none has ever come close.

Doerflein selflessly stayed with Knut round the clock for 150 straight days, hand-feeding the cub with milk and porridge through the nights. Knut, weighing 800 grams, had been the first polar bear born at the zoo in 33 years.

Knut, who grew to 28 kg within six months, would have died shortly after his birth without Doerflein's care. Doerflein's twice daily "Knut shows" drew more than 1 million viewers and were staged for several months until Knut grew too large.

Doerflein died aged 44 in 2008, three years before the cub.

(reporting by Marina Adami; editing by Erik Kirschbaum and Gareth Jones)