Panda death stuns Berlin after polar bear euphoria. Berlin Zoo on Tuesday (March 27) denied media allegations that Knut the celebrity polar bear cub was responsible for the sudden demise of one of its older attractions, a 22-year-old panda who was found dead in her cage. Just four days after the euphoria over the debut of three-and-a-half-month old "Cuddly Knut", the mysterious death of Chinese-born Yan Yan stole the headlines in Tuesday's German newspapers. Top-selling Bild reported that the influx of visitors to the zoo -- about 30,000 a day -- could have stressed the black and white bear, who spent much of her time lying on her back chomping at bamboo shoots. "Lots of people gave up on seeing Knut because of the long queues, so they went to see Yan Yan instead. She seemed intimidated and anxious," wrote the paper, suggesting Yan Yan could have had a heart attack. Berlin Zoo denied any link. The zoo has kept the lifeless panda in a cold store overnight and will conduct an autopsy to establish the cause of death. "Our female panda Yan Yan died late afternoon yesterday" Berlin Zoo bear curator Heiner Kloes told Reuters TV. "We found her dead in her enclosure. We are all very sad. Unfortunately, we can not tell yet what caused her death. From the way we found her we expect she died of natural causes, that she died peacefully. But we can only be sure after the autopsy we will conduct today", Kloes continued. Yan Yan, Chinese for "The Beautiful One", was brought to Berlin in 1995 from Beijing and was a star years before Knut the polar bear was born. Yan Yan leaves behind the 28-year-old Bao Bao, the world's oldest panda, according to the zoo spokesman. Knut, meanwhile, is putting on weight and will be allowed to sleep on his own within a couple of months, says the zoo vet.