A case of H7N7 avian flu has now been confirmed in Lancashire.
A temporary control zone imposed on Friday at the affected farm has now been replaced by a 10km surveillance zone and an inner 3km protection zone, DEFRA have said.
Restrictions remain in place and the humane culling of all birds at the farm in Goosnargh is continuing.
Public Health England has confirmed that the risk to public health from this strain is very low.
The Food Standards Agency has said there is no food safety risk for consumers.
The restrictions mean that all poultry farms within the 10km control zone around the infected premises are not allowed to move poultry, captive birds or other mammals except under licence.
Chief Veterinary Officer Nigel Gibbens said: “Final tests results have confirmed a case of avian flu at a farm in Lancashire.
“Restrictions put in place last week will continue and the humane culling of all birds at the site is progressing.
“These actions are part of our tried and tested approach to dealing with previous outbreaks.
“Public Health England has confirmed that the risk to public health from this strain is very low.
“The Food Standards Agency has said there is no food safety risk for consumers.
“Bird keepers should remain alert for any signs of disease, report suspect disease to their nearest APHA office immediately and ensure they are maintaining good biosecurity on their premises.”
An investigation into the case is ongoing.