Last week, the World Health Organisation warned that the virus, known to have killed 27 people in Vietnam and 12 in Thailand over the past year, was endemic in Asia and appeared to be evolving in ways that favoured the start of a human outbreak.

"So far, the infection of humans by humans is the main concern, but this hasn't happened to a worrying extent," EU Health and Consumer Protection Commissioner Markos Kyprianou told reporters. "And some scientists say a pandemic is overdue."

"We are insisting that member states have 'preparedness bans'. We will have test exercises on member states for dealing with these issues. It's not only the time required to prepare a vaccine but also the time for industry to get them ready."

In Europe, several countries have found themselves forced to react quickly to a bird flu outbreak in their poultry sectors. The Netherlands, for example, slaughtered a quarter of its poultry after an outbreak infected 90 people and killed one.

What scientists fear most is that the bird flu virus could mutate if it infected a person sick with ordinary flu, or got into an animal hosting a human flu virus, such as a pig.

If the deadly H5N1 strain of the virus were to merge with a human flu virus, they say, then it could produce a strain capable of sweeping through a human population without immunity, possibly killing millions worldwide.