More than 70 cat lovers chanted "Sack the zookeeper!" in front of the Beijing Zoo on Sunday, demanding an investigation into the deaths of two stray cats living on the zoo grounds, where volunteers are trying to establish a cat sanctuary.

The protest is the latest in a cat-and-mouse game between cat lovers, who have been building shelters for the stray animals, and zoo officials, who have been knocking them down, claiming the cats could spread contagious diseases among the other animals.

A woman surnamed Sang, who feed cats in the zoo and participated in the protest, said that a dog chewed a small cat to death several days before.

"I can tell it's a big dog because the shelter for the cat is totally damaged," said Sang, noting she saw dog footprints.

Sang says volunteers did not realize the seriousness of this issue until two days later, when more dog footprints were found, and another cat were found dead, with lots of wounds, from either dog bites or being beaten.

Another volunteer, surnamed Yan, said that he saw dogs in the zoo on Saturday. "It was after 7 pm when I saw five medium-sized dogs walking freely about the zoo," said Yan. "And I immediately reported it to the guards."

Zoo guards denied that dogs could enter the grounds, or that the resident dogs could escape from their cages.

Ye Mingxia, a spokeswoman of the Beijing Zoo, said she was unaware of the protest. In October, the zoo's new director demolished shelters for stray cats. The zoo built 20 new shelters, then tore them down this month.