Defra yesterday moved to prevent the spread of the deadly H5N1 avian flu outbreak in Norfolk by ordering the slaughter of 22,000 poultry.

It identified four premises close to the original outbreak at a farm on the Norfolk/Suffolk border as 'dangerous contacts' and ordered all birds on the sites to be culled.

“At this stage we have not confirmed disease on any of these four premises,” said acting chief veterinary officer Fred Landeg. “This is a precautionary measure taken to prevent any potential spread of the disease.”

Imported day-old ducklings from the Netherlands are being investigated as a possible source of outbreak, according to reports in The Times. The farm receives regular supplies of ducklings delivered by a Dutch exporter, the report claims.