A laboratory at Hong Kong University detected a reassortant made up of a swine influenza virus and the pandemic H1N1 virus in a sample obtained from a slaughterhouse pig. It is the first reported reassortant between the two types of viruses. The finding doesn't pose a public health risk or present any food-safety issues.

Dr Malik Peiris, a microbiology professor who heads HKU's surveillance program, said in the statement that the finding isn't unexpected, likely occurs worldwide, and was only detected in Hong Kong because of intensive surveillance. He said tests are under way to further characterize the virus.

China produces 600 million to 800 million pigs each year and that most swine are not kept in biosecure buildings, as they are in the United States.