Wild birds were blamed last February when bird flu was discovered at a Bernard Matthews farm in Suffolk.

Those claims never rang true - migrating birds were on their way out rather than on their way in - and so it proved.

Claims that wild birds are responsible for this week's outbreak may also prove too hasty. Most migrating birds have arrived for the winter and no dead wild birds have been found to be carrying bird flu.

Dr Mark Avery, Conservation Director of the RSPB, said: 'If migrating wild birds were carrying bird flu, their corpses would have been found north and east of the UK, the routes that migrating wildfowl take. But there have been no recent reports of wild birds dying of bird flu in the countries on their migration routes.

'Jumping to conclusions over the source of bird flu could blind us to courses of action that should be taken. We can't rule out wild birds as carriers but we're not even close to knowing that claim is true.'