Britain is going to provide the entire population with vaccines in the case of a flu pandemic.
Health Secretary Alan Johnson said a flu pandemic was "one of the most severe risks" facing the country, telling lawmakers that he had signed an agreement to secure the delivery of enough pandemic flu vaccines to cover every citizen.
Experts would formulate a vaccine once the strain of the virus has been identified, but it would take several months before a vaccine could be produced and distributed to the population.
Officials said it was impossible to predict when the next pandemic would strike and what form it would take.
Two outbreaks of the deadly H5N1 strain of bird flu have been confirmed recently in eastern England. H5N1 is difficult for humans to catch, but experts fear it could mutate into a form that spreads easily among people, potentially sparking a flu pandemic.
The last flu pandemic - Hong Kong flu - struck in 1968, leading to approximately 1 million deaths worldwide and 80,000 in Britain, a Health Department spokeswoman said on condition of anonymity in line with department policy.
"We don't believe an influenza pandemic is imminent," the spokeswoman said.
The World Health Organization recently praised Britain for its preparedness to tackle a global flu outbreak.