Swan 'may have died outside UK'
A dead swan found in Fife which tested positive for the deadly H5N1 strain of bird flu may not have died in the UK, Whitehall sources have told the BBC.
The "working hypothesis" is the bird could have died in another country and been washed up on the Scottish coast.
Ministers are considering bringing in targets to regulate the time between reporting a dead bird and tests being completed, according to the sources.
No birds have tested positive for H5N1 since the swan was found last week.
Early test results suggested the swan found at Cellardyke had an almost identical virus to birds found in Germany.
The RSPB is hopeful that this, combined with the lack of any further cases, means the swan could be a "one-off".
The society's spokesman Andre Farrar said: "If this individual bird washed up from outside the UK... that does favour the theory that this is a one-off.
"It does build on the fact that we've seen no more positive results in the few days after the discovery of the first swan."
The H5N1 virus cannot pass easily from one person to another and therefore currently does not pose a large-scale threat to humans.But experts fear the virus could gain this ability if it mutates. They say it could trigger a flu pandemic in its new form, potentially putting millions of human lives at risk.
Microbiologist Professor Hugh Pennington said it was "always a possibility" the bird was infected near the German island of Ruegen, which saw an outbreak of the disease last month.
"The optimists would like it to have been infected in Ruegen and then washed by currents to Britain," he told Radio 4's Today programme.
He said the pessimistic view was that the swan caught the virus locally, meaning birds would still have the disease but not been detected.
He added that bird flu would not be "a foot-and-mouth situation - the virus is not going to go on the rampage".
Experts are still testing birds found near Cellardyke, and a UK helpline has had thousands of reports of dead birds.
A six-mile (10km) surveillance zone and 1.8 mile (3km) protection zone in place around Cellardyke will remain for at least 30 days from the day the swan was found.
A wild bird risk area has also been established which includes 175 registered poultry premises, containing 3.1 million birds, 260,000 of which are free-range.
Over 8,000 calls have been made to the authorities in the last week by members of the public reporting dead birds.
Officials say 1,100 birds have been tested since February.