Some 35,000 chickens will be slaughtered on a farm in eastern England following the discovery of bird flu among a number of dead poultry there, an environment ministry spokesman said. Initial tests on the fowl found the H7 strain of avian influenza rather than H5N1, which is potentially lethal to humans, the Department for the Environment, Food and Rural Affairs said.
The spokesman said further tests were being carried out to determine the N-strain of the virus.
The H7 strain of bird flu itself has the potential to be highly pathogenic and a grave threat to poultry.
Britain suffered sporadic outbreaks of H7 in 1985 and 1977.
The environment ministry said in a statement: "Preliminary tests have this evening indicated that the avian influenza virus is present in samples from chickens found dead on a poultry farm near Dereham in Norfolk."
All other fowl on the farm will be slaughtered as a precautionary measure, it said.
The spokesman told AFP: "There are some 35,000 poultry on the farm."
Restrictions have been placed on the location and may be reassessed following further results from the laboratory.
Britain's first case of the H5N1 strain of bird flu was discovered in a wild dead swan in Scotland earlier this month.
But no other birds have since tested positive for H5N1, which has caused the deaths of more than 100 people, mainly in Asia.
