More than 30,000 stray cats have been sterilized in Beijing in a government-backed NGO project since July 2006, an official said Saturday.

More than 100 animal hospitals and clinics have joined the Trap Neuter Return (TNR) project, providing more than 1,000 quotas every month for free sterilization, said Wei Haitao, veterinary chief of the city's agriculture bureau.

"NGOs can take stray cats to designated animal hospitals for free sterilization and then return them to streets," said Louis Liu, president of Beijing Small Animal Veterinary Association, sponsor of the project.

The 11 members of NGO New Beautiful World (NBW) helped to sterilize 1,700 cats in 2009.

"Sterilization is important for the well-being of stray cats. My friends and I just found 10 stray cats to be sterilized in the Palace Museum this morning," said NBW volunteer Yao Yao.

The number of stray cats has been increasing rapidly in Beijing as stray cats are better-fed and more domestic cats are being abandoned by relocated families, Wei said.

The wandering cats are threatening squirrels, birds and small animals, Wei added.

He said the project helped to contain the number of stray cats and the spread of animal diseases.