A man feeds pigeons in Split, Croatia. (Reuters)

Warsaw, March 6 (Reuters): Avian flu extended its spread across Europe as Poland confirmed today that two dead swans had the virulent H5N1 virus and Austria reported that several cats had been infected.

Experts from the WHO, meeting in Geneva, said the spread of bird flu was unprecedented and the threat of a human pandemic would not go away.

China said yesterday the H5N1 virus had killed a man in southern Guangdong province, which borders Hong Kong. There had been no reported outbreaks in birds in the area where he died and experts in Hong Kong urged authorities to find the source.

The WHO has previously confirmed 94 human deaths from bird flu since late 2003. The virus remains essentially an animal disease which humans contract through close contact with infected birds.

The virus is currently spreading rapidly among wild birds and has reached 15 new countries over the past month.

Austria said the H5N1 virus has been found in several cats in the southern region of Styria. A dead cat in northern Germany was found to have the virus last week.

The WHO has played down the threat to human health from infection in domestic cats, but the news has alarmed pet-loving Europeans. It is thought that cats are getting the virus by eating infected birds.