According to the Department for Environment, Food and Rural Affairs, tests on the birds indicate the presence of the lethal strain of the virus.
Gordon Brown states the case
Gordon Brown has said that the government was doing everything it could to prevent the spread of the latest outbreak of bird flu after three dead swans were found on a nature reserve in Dorset.
Duck/ Gull cause of bringing disease
The swannery is one of the most popular tourist attractions in England and is home to 300 pairs of mute swans. The birds stay within the locality and do not migrate.
Ornithological experts believe the disease has been brought into the country by a duck or gull.
A culling of the rest of the swan colony will not take place as this may disperse bird a field. Defra (Department for Environment, Food and Rural Affairs) has the authority to order the culling, however it is believed that it is not feasible to control the disease in wild bird populations.
Poultry keepers have been told to keep all free-range and organic birds indoors and to ensure they are kept away from wild birds.
A 3km wild bird control area and wider 10km monitoring area has been imposed around the swannery, which includes Chesil Beach and Portland Bill.
â€œWhile this is obviously unwelcome news, we have always said that Britain is at a constant low level of risk of introduction of avian influenza,â€ said Fred Landeg, acting Chief Veterinary Officer.