The culling of 170,000 birds has begun after it was confirmed a strain of H7N7 bird flu was detected in poultry at a Lancashire farm.
The department for environment, food and rural affairs (Defra) said the strain was found on 10 July and said a 3km protection zone had been put in place.
Officials say there is a low risk from the outbreak and Public Health England has confirmed 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, while Public Health England has confirmed the risk to public health from this strain is very low.
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."
Bird keepers should remain alert for any signs of disease and report suspect issues to their nearest APHA office immediately and ensure they are maintaining good biosecurity on their premises.
There had been previous outbreaks of the virus in Yorkshire in 2014 and Hampshire in February. An investigation into the outbreak is ongoing.