The slaughter of thousands of turkeys on a farm infected with the potentially deadly H5N1 strain of bird flu is being completed, as scientists attempt to track down the source of the virus.
There were immediate concerns the outbreak may dent sales of poultry, although health officials have said there was no evidence anywhere in the world of the disease being picked up through food.
Although 164 people have died from H5N1 since January 2003, mostly in Asia and the Middle East, the Health Protection Agency has reassured the public it is only transmitted through direct contact with poultry.
And industry figures have urged consumers to heed advice from Defra which said no infected birds have entered the food chain.
Charles Bourne, chairman of the National Farmers' Union (NFU) poultry board, said: "There is the likelihood that there could be an effect on sales and that is really what is going to hit me.
"If chicken sales drop by 5%, that means we produce 16 million chickens a week in this country and some 500,000 are not wanted. That will affect the market and prices will go down. Of course we are concerned."
But the major supermarkets have reassured customers their poultry and egg products were safe and supplies were unaffected.
Meanwhile, officials said the risk posed to humans by the highly pathogenic Asian version of avian flu found on a Bernard Matthews farm at Holton, near Halesworth, Suffolk, is "negligible".
But the Government is preparing "very seriously" for the remote possibility the disease - which can be transmitted to humans - could mutate into a form which causes a flu pandemic.
Health Secretary Patricia Hewitt said: "We are preparing very, very seriously and thoroughly for the possibility of a pandemic flu. It is a very remote risk but if it did happen it could be very serious indeed."
