It has been officially confirmed that the deadly bird flu virus has arrived in Britain. Authorities said a dead swan found in Scotland did have the feared H5N1 strain.
Both the Royal Society for the Protection of Birds and the National Farmers' Union had earlier said that the virus was responsible for the death of the swan in Fife, Scotland.
Twelve more swans and two other birds, all from Scotland, are now being tested for the virus.
The swan confirmed as having H5N1 had washed up in the harbour of the coastal village of Cellardyke a week ago. It was not removed until the day after it was reported by a member of the public.
An RSPB spokesman told Sky News: "The critical thing here is to keep it in perspective.
"It's H5N1 - it's still a bird disease. It does not mean a human flu pandemic that's landed in Britain."
The swan was a mute, which is one of three types in the UK which do not normally migrate, so it could have come into contact with other infected birds.
It had been dead for eight days but tests were not carried out until late on Wednesday after initial investigations found it had the less serious H5 type of virus.
Chief veterinary officer Charles Milne told an Edinburgh press conference a "wild bird risk area" would be set up in a 2,500-square kilometre area to the east of the M90 motorway.
He said: "We are proposing to issue a veterinary directive to owners of poultry to house their birds where possible."
He said that if that was not possible, they would be expected to put in place measures to separate their birds from wild birds.
Gatherings of birds in that area would be banned, Mr Milne said, and there would be enhanced surveillance of wild birds.
A statement by the Scottish Executive said: "There is no reason for public health concern.
"Avian influenza is a disease of birds and whilst it can pass very rarely and with difficulty to humans this requires extremely close contact with infected birds."
Researcher Dan Brown, who first reported the swan to the authorities, said it appeared to have been "pecked at or eaten by something. It was torn open".
The H5N1 strain has killed more than 100 people worldwide.
Experts fear, if it mutates into a form that can pass between people, millions could die across the globe.