Bernard Matthews Farms has confirmed that flocks on two of its small breeder units have tested positive for low pathogenic avian flu.
DEFRA vets tested birds on the two units, after the company reported an unusual drop in egg production levels.
Subsequent tests were positive, but DEFRA stressed that it is not the highly pathogenic H5 or H7 sub-type.
Bernard Matthews said: “As a precautionary measure and out of a duty of care for our employees, we have sought guidance from the Health Protection Agency (HPA).
“They have advised that this type of avian flu poses a very low risk to human health and do not recommend providing Tamiflu treatment to our staff.”
The two small breeder farms will remain under movement restrictions until further tests have been completed by DEFRA.
The company added that its other operations continue to run as normal.
Avian flu was last found in a poultry flock in June 2008, when an outbreak of the highly pathogenic H7N7 hit a free-range egg unit near Banbury, Oxfordshire.