A 36-year-old bear which performed during the 1980 Moscow Olympics has been kept for the past two years in a rusty old bus on the outskirts of St Petersburg.

Animal rights activists say the bear and other retired circus animals receive only minimal care in cramped and stinking cages. Katya the bear was a long-time star of the St Petersburg State Circus on Fontanka, where night after night it and another bear rode motorcycles around the ring.

During the 1980 Games, the bears performed at a ceremony opening the football competition in St Petersburg, then called Leningrad. Katya also appeared in two films in the 1980s. Since its retirement in 2009, Katya and the painted bus on which it once toured with the circus have not left a car park near a busy road. The aging bear spends the hours jumping up and down in its cage and trying to crack the rusty metal railings with its chipped and yellowed teeth. Dozens of other retired circus animals also live in the cramped cages inside the bus and a minivan parked nearby.

Some occasionally are taken out to accompany photographers to the centre of town to have their pictures taken with children and tourists. Others never get washed or examined by veterinarians, animal rights activists say. "They can't move normally and start going crazy," said Zoya Afanasyeva of the Vita animal rights group, as she stood by Katya's sweltering bus on a hot summer day.

The bus where the bear is kept caged. Photograph: Dmitry Lovetsky/AP

"Apparently they are being taken care of, but not more often than once a day, and this care is perfunctory because the smell here in the parking lot is unbearable." Klava the bear shares a small cage with Pasha the boar. Birds with atrophied muscles live next to cats that do not meow and stare straight ahead with pus-covered eyes.

The circus director, Viktor Savrasov, said the animals are cared for and Katya's fate would have been worse if her trainer had agreed to have the bear put to sleep.

"Whatever happened, she did not leave her," he said of retired trainer Natalya Arkhipova, who still visits to feed Katya.

Animal rights activists have long urged Russia's government to strengthen animal protection laws.