The farm at the centre of the latest bird flu outbreak was named today as Witford Lodge Farm at Hockering, Norfolk.
Police officers stood guard at the entrance to the farm after a number of dead chickens tested positive for the virus.
All of the 35,000 chickens at the farm will now be slaughtered, as bio-security measures are put in place to prevent the spread of the virus.
Tests are being carried out today to establish the exact strain of the virus but preliminary test results show that it was likely to be the H7 strain rather than H5N1, which has been responsible for the deaths of more than 100 people, mainly in Asia.
"Preliminary tests have indicated that the avian influenza virus is present in samples of chickens found dead on a poultry farm near Dereham in Norfolk," said the Department for Environment, Food and Rural Affairs last night.
"Further tests are being carried out to determine the strain of the virus.
"The preliminary test results show that it is likely to be the H7 strain of avian influenza and not H5N1.
"As a precautionary measure, birds on the premises will be slaughtered on suspicion of an avian notifiable disease."
The spokeswoman added that restrictions had been placed on the firm, and that further action may be taken when the additional laboratory results were known.
Last month a wild swan that was found dead in the harbour of a coastal town in Scotland was found to have died of avian flu.
That bird, which was discovered in Cellardyke, Fife, tested positive for the deadly H5N1 version of the virus
Although hundreds of wild birds have been tested in the last few months, the swan in Fife remains the only case of H5N1 to have been discovered in the UK.
While H7 versions of the disease can be highly pathogenic among poultry, and have crossed the species barrier to humans, outbreaks in people have been less serious than those of H5N1.
Some experts fear the H5N1 virus could mutate and develop into a flu pandemic which could put millions of lives at risk.Reuse content