Bird flu was confirmed inside the borders of the European Union today when Greece said that at least one case had been detected on an island in the Aegean.

The Agriculture Ministry said the H5 virus had been detected on a turkey on the island of Chios. It was not yet clear whether the bird was infected by the H5N1 sub-strain, which has claimed at least 60 human lives in Asia.

Chios is in the eastern Aegean, only a couple of miles at its closest point from western Turkey, where an outbreak of bird flu at a turkey farm, confirmed as H5N1, has brought a major cull. The virus has also been found in wildfowl in Romania's Danube delta.

News of the outbreak in Greece came as Patricia Hewitt, the Health Secretary, told the Commons that the Government was taking the prospect of a bird flu pandemic - if it crosses across into humans - "very seriously" and its latest contingency plans would be published on Thursday.

"As the chief medical officer has stated, most experts believe it is not question of whether there will be another severe influenza pandemic, but when," she said. "We take this threat very seriously. The Government has been taking increasing action, particularly over the last 12 months, to prepare."

Ms Hewitt said that a flu pandemic could affect a quarter of the population, adding: "We estimate there could be at least 50,000 deaths as a result of the pandemic, compared to around 12,000 flu-related deaths every year, and it could be significantly more."

A team of British experts in infectious diseases are to visit South-East Asia, where millions of birds have been slaughtered, to investigate first-hand how best to tackle a deadly bird flu pandemic. The fact-finding mission from the Medical Research Council will visit Vietnam, China and Hong Kong,.

And officials in Croatia said today that the country had started testing dead birds found by citizens for possible avian flu, although no cases had yet been confirmed. The former Yugoslav republic is on a key migratory route linking the Russian Far East and northern Europe, where millions of birds overwinter after leaving Siberia.

"Until recently, people simply did not notice dead birds but now they see them everywhere and immediately call the police," a Croatian agriculture ministry official told Reuters, commenting on a newspaper report that ten dead starlings found near Zagreb were sent to a veterinary institute for testing.

"We react promptly to every report, take samples and analyse them, but so far nothing has been found. People are really overreacting, but we are taking all precautionary measures," the official said.

And staff at the Wildfowl and Wetland Trust at Slimbridge, Gloucestershire, have started testing some 2,000 birds to make sure that none of their resident flocks of geese and ducks are carrying avian flu. Thousands of migratory swans and geese will be arriving at the centre over the next few weeks.

The Government’s chief medical officer warned that at least 50,000 Britons could be killed if the disease takes hold among the human population. If the virus mutates into an aggressive strain, as many as 750,000 could die.

Times Recommends

• No apology for Germany’s own Nazi victims
• Intricate web of fear and hope tying down deal
• Victims remembered a year after Mumbai attacks