Germany confirmed the H5N1 bird flu virus in three more wild birds in the southern state of Bavaria on Monday, bringing the total infected cases to six since last weekend.

Since three wild bird found dead in Nuremberg in northern Bavaria tested positive for the deadly H5N1 strain on Sunday, three more cases have been confirmed, with five swans and one goose infected, the Friedrich Loeffler Institute, a veterinary institution, said on Monday.

Local authorities in Nuremberg has established a restricted zone within a radius of about four km and ordered local poultry farmers to confine all poultry to closed stalls. Nuremberg officials also warned dog owners not to allow their pets to run freely in the quarantine zone.

Although the German government did not expect the Nuremberg outbreak to spread to other regions, German Agriculture Minister Horst Seehofer warned that the virus was still present in the environment.

The H5N1 bird flu virus has been found in geese and turkeys in a total of four farms in Hungary, Britain and the Czech Republic this year, but not yet in wild birds.

According to the World Health Organization, the H5N1 virus has killed nearly 200 people out of more than 300 cases globally since 2003. Health experts fear that H5N1 could some day develop the characteristics of seasonal flu and begin spreading easily among people, causing a global outbreak that could kill millions.