In this, the Year of the Dog in the Chinese calendar, the pets enjoy the Coolbaby Dog Theme Park in Beijing. [The New York Times]

The small apartment was the equivalent of a safe house: Ms. Wu, head of a local animal rescue association, had stashed about 10 strays and handicapped mutts. She said the dogs, one paralyzed, another recovering from a broken spine, should be exempt from a new "strike hard" campaign against dogs in Beijing. But she was not certain.

"They cannot move out these dogs!" she declared. But then she hesitated slightly, "How could they do it?"

Beijing is a city of at least 12 million people and at least a million dogs, about half of which are unregistered and deemed fugitives in the eyes of the local police.

The complication, of course, is that many of these fugitives are also beloved pets, so confrontation is almost inevitable and has been rising in recent weeks as the police have begun a swift and harsh crackdown against illegal dogs.

The police have already rejected applications by different pet advocacy groups to stage demonstrations. On Saturday, at least 100 police officers blocked roads as a large crowd congregated outside the city zoo. One participant said officers manhandled and detained more than 20 people who tried to hand out leaflets promoting animal protection. The people were released later the same day.

The conflict is over city regulations that limit households in eight designated districts to a single dog and also forbid people from owning large dogs like golden retrievers and huskies.

The regulations, considered misguided by many dog owners, were introduced in 2003 but have been only loosely enforced as the city's pet industry has boomed. Dogs in Beijing can now eat at a dog restaurant, be groomed at a dog boutique and swim in an outdoor dog lap pool.

Last Tuesday, though, Beijing newspapers carried a notice about the new campaign, under way since October, concerning "pet dog management work." It said households with too many dogs, or with big dogs, would have 10 days to relocate them. In essence, owners had 10 days to get rid of the dogs or the police would do it for them.

The note also promised to pay rewards to people who helped the police catch neighbors violating the dog rules.

Anxiety and outrage have quickly spread among dog owners. Several reported that the police were already apprehending large dogs in apartment compounds and had even entered individual apartments to seize some dogs. Web sites posted photographs of dogs crammed into holding pens at dingy city pounds. Another Internet posting warned that a slaughter of stray dogs and cats would begin next week.

"We are all worried," said a woman who owns several dogs and asked not to be identified for fear the police would try to seize her pets. She is building a kennel in her uncle's village in nearby Hebei Province to ensure that her dogs and others are not seized.

Rabies is the primary reason offered for the new crackdown. Nationally, China reported that 1,735 people died from the disease between January and August, a 29 percent increase from the period a year earlier. The Ministry of Health said growing numbers of people were taking dogs as pets without properly vaccinating them.

But what has horrified pet advocates worldwide is the brutal solution that some places in China have adopted to solve the rabies problem. This summer, officials in one section of Yunnan Province ordered an extermination campaign that led to the slaughter of more than 54,000 dogs. Another smaller extermination drive was held in Shandong Province.

Grace Ge Gabriel, the Asia director for the International Fund for Animal Welfare, said her group agreed that dog owners should vaccinate their pets and register them. But she said Beijing's current ban against big dogs was wrongheaded because it was based on the premise that they are more vicious.

She also said that using rabies to justify the crackdown was misleading because Beijing did not have a rabies problem, a point confirmed by a state media report.

Last Friday, at the Huayuan Street police precinct in the northeastern quadrant of the city, a red-and-white banner stated: "If You Have a Dog, You Need a License." Inside, at the Dog Management Office, Shi Chenhe said he had registered 10 new dogs in recent days and argued that rabies and dog bites were serious problems in Beijing.

He said officials wanted to ensure that no one was bitten and injured during the 2008 Olympics. "Of course, it is related to the Games," Mr. Shi said. "Everything needs to be cleaned up before the Olympics."

Mr. Shi said that officers in his precinct had not begun cracking down on illegal dogs but that each police district was handling the issue differently. "We're waiting to be notified," he said.

Ms. Wu, the head of the association for stray dogs, has been racing to different meetings with dog advocates, trying to find a solution, and some dog owners have told her they will defend their dogs at any cost.

"People are saying that if they have to, they will fight back," Ms. Wu said. "I told the young people that they shouldn't fight back. It is the order of the government. If you fight back, it will hurt the dogs in the long run."

Across town at a trendy pet store, Man Qingwei, 32, helped hold down his two border collies on Friday afternoon as an attendant cleaned the dogs' ears with a cotton swab. Mr. Man bought the dogs recently even though he knew their size violated city regulations. "Of course, we hide them," Mr. Man said as his girlfriend patted the collies. "I have to sneak them out quickly into my car."

Mr. Man said he wanted dog owners to organize to force the city to change the rules. "I think the one-dog rule is ridiculous," he said. "It's a matter of one's personal life and tastes. You should be able to have as many dogs as you like."

Mr. Man said that he and his girlfriend owned several dogs but that the new regulations were making ordinary tasks difficult. "We can no longer walk them," he said. "I'm thinking about buying them a treadmill."