A leading British scientist attacked the government on Sunday over its contingency plans to deal with a human bird flu pandemic, saying over two million Britons could die.

Professor Hugh Pennington, president of the Society for General Microbiology, told the Independent on Sunday a pandemic was both imminent and inevitable.

“If the virus moves into people there will be no stopping it,” he said. “It will be here before we know it.”

Health experts fear that the H5N1 bird flu virus that has killed 47 people in Asia could mutate into a strain easily transmitted in humans that could trigger a pandemic similar to the Spanish Flu in 1918 that killed between 20 million to 40 million people worldwide.

So far, though, there is no evidence of sustained person-to-person transmission of the virus.

Medical experts suggest that around one in four people in Britain could be affected by an influenza pandemic. Without counter-measures, they estimate it could kill about 50,000.

Pennington said that was overly optimistic.

“They (the government) hope that by the time they have to spend money the problem will have gone away,” he said.

Britain has ordered enough drugs to treat about one quarter of the population and they will be delivered over the next two years. They will not prevent a pandemic but could mitigate its effects.