Preliminary tests suggest that the H7 strain of the avian influenza virus has been found on a poultry farm near Dereham in Norfolk.
Further tests will be carried out on Thursday (26 April), to confirm the strain of the virus.
DEFRA has announced that as a precautionary measure birds on the premises will be slaughtered on suspicion of an avian notifiable disease.
Restrictions have been placed on the farm.
When the additional laboratory results are known further action may be taken.