The European Union said Wednesday that the dangerous H5N1 strain of bird flu had been found in Croatia, while authorities said a second parrot that died in quarantine in Britain was also infected with the virus.

The Chinese government, meanwhile, announced that a bird flu outbreak had killed 545 chickens and ducks in central China -- the country's third case of the disease in two weeks. A government laboratory confirmed that the virus was the H5N1 strain, which has caused the devastation of poultry populations in Asia and killed 62 people since 2003.

The Croatian case was confirmed by a British lab that tested samples from six swans found dead last week in a nature park. The European Commission, the E.U.'s executive body, on Monday issued a precautionary ban on imports of live poultry, wild birds and feathers from the Balkan country.

Croatia is the latest European nation to report a case of H5N1 as it moves west. It was discovered earlier in Romania, Turkey and Russia.

Health experts fear that the virus, which is difficult for humans to acquire, will mutate into a form that is easily spread from person to person, possibly sparking a global pandemic that could kill millions.