UK scientists are carrying out tests to see if a parrot that died from bird flu in quarantine had the H5N1 strain that has killed at least 60 people in Asia.
Birds across Europe are being kept indoors as a precaution
It has been established the parrot had bird flu H5 - but it was unclear where it caught it.
The bird came from South America, and was held with 216 birds from Taiwan. As the death was in quarantine, the UK's disease-free status is unchanged.
Experts said detecting the virus showed the quarantine system was successful.
Meanwhile, the EU is banning Croatian poultry imports after H5 was found.
As well as in Asia, so far bird flu - in some cases the H5N1 strain - has been found in Romania, Greece and most recently, Croatia, as well as in a nearby area of Turkey.
It is thought it was carried to those countries by wild birds migrating from Asia.
The parrot - which was being held in a bio-secure unit at an undisclosed location - is the first confirmed case of bird flu in Britain since 1992.
The bird, from Surinam, was part of a mixed consignment of 148 parrots and "soft bills" that arrived on 16 September.
All the birds in the quarantine unit have been culled, said the Department of the Environment, Food and Rural Affairs (Defra), and people who had contact with them are receiving antiviral treatment as a precaution.
UK chief veterinary officer Debby Reynolds said the incident had shown the importance of the UK's quarantine system.
"We have had similar incidents in the past where disease has been discovered but successfully contained as a result of our quarantine arrangements," she said.
A Defra spokeswoman said all birds in quarantine were tested for both bird flu and Newcastle disease before being released, as standard policy.
The head of the Medical Research Council, Professor Colin Blakemore, said the discovery of the virus would have been more worrying in a migratory bird.
He told the BBC: "Clearly birds in quarantine are not in contact with domestic birds, with farm birds in this country."
Professor Blakemore is leading a team of scientists leaving for Asia on Sunday to research bird flu.
They will visit China, Vietnam and Hong Kong.
Aberdeen University microbiologist and bird flu expert Professor Hugh Pennington told BBC News Britons should not be alarmed by the discovery.
"The bird flu has been doing the rounds of the Far East for about 10 years and it hasn't mutated yet into the form that we really fear - the form that could infect people on any scale at all - and it may never do that," he said.
Professor Pat Troop, head of the Health Protection Agency, said officials' only concern was the virus mutating.
"Our main worry is... when the bird flu mixes with the human flu to create a new human flu strain," he said.
The RSPB said the parrot's death showed there were "serious conservation, animal welfare and health questions" about the trade in wild birds.
"Holding the presidency of the European Union, the UK should press all member states to halt the import of millions of wild-caught birds into the EU as part of its biosecurity measures."
The RSPCA has also called for the EU to immediately ban wild-caught bird imports because of the risk of bird flu.
RSPCA's head of internal affairs David Bowles said: "Controls in the exporting countries are not working which means that the EU's rules have a fatal flaw in them to prevent disease entering the EU."