The World Health Organization has criticised Chinese plans to slaughter 10,000 civet cats in an attempt to curb the spread of the deadly Sars virus.
Many researchers believe Sars could have jumped from animals to humans
The news comes as the organisation said tests confirmed China's first case of the illness in six months.
Researchers in Hong Kong have linked the strain the victim is carrying to a similar virus found in civets in China.
But the WHO said slaughtering the animals could pose a public health risk and may destroy scientific evidence.
Officials in China's Guangdong province said they hoped to complete the civet cat slaughter by Saturday.
But the WHO said the move was radical and that the man's case remains an isolated one which does not constitute a public health emergency.
Part of mongoose family, distant relative of feline cat
Weasel-like face, cat-like body
Served in wild game restaurants
Estimated 10,000 in Guangdong markets
May have been the source of the virus which jumped to humans
It also warned that not enough research had been conducted into possible links between the civet cat and Sars (Severe Acute Respiratory Syndrome).
"At this point in time... without seeing that data, there is no conclusive evidence that civets are the animals that carry the Sars virus," WHO Sars team leader Judy Hall told the BBC.
"We would call on the government of China to do a risk assessment before slaughtering these animals."
Civets are small, weasel-like animals considered a delicacy in China's Guangdong province.
Many researchers believe the strain of Sars which killed hundreds of people last year in China and across the globe could have jumped species to humans from an animal like the civet.
Zhong Nanshan, director of the Guangzhou Institute of Respiratory Diseases, told a Hong Kong news conference on Monday that the virus in the latest case appeared to be slightly different to that which originated in Guangdong in November 2002.
The researchers added that they had found a virus very similar to this new strain in civet cats, suggesting it had jumped from the animals to humans.
Mr Zhong said the suspected Sars carrier - a male 32-year-old television producer - had claimed not to have eaten any wild animals before he fell ill, but did admit to touching at least one rat.
The man is currently in hospital in the city of Guangzhou in the Guangdong province.
An additional 25 people who had contact with the patient have been isolated, but none appears to be infected.
Sars killed 349 people on China's mainland last year during the global outbreak.
But BBC correspondent Louisa Lim says people in China seem confident that the government now has the experience to deal with Sars both quickly and openly.