Thousands more birds are to be culled after a fifth outbreak of avian flu was detected in North Yorkshire.
The deadly virus was confirmed in commercial poultry at a site near Thirsk just hours after a national lockdown on birds came into force this week.
Two sprawling temporary control zones of 1.8 miles and 6.2 miles have been put in place around the affected site.
The outbreak was discovered on Monday just hours after bird-keepers across the UK had moved their flocks inside following government orders.
The action was taken in a bid to prevent a more widepread catastrophe following four separate outbreaks of the highly contagious bug in the region.
Those outbreaks followed an initial eruption at a site in Worcestershire in late October.
Supplies of poultry are not expected to hit Christmas supplies and there is no known threat to people, the Department for Environment, Food and Rural Affairs has said.
But, in addition to keeping birds and poultry indoors, keepers have been told to take extra precautions such as regularly cleaning and disinfecting clothing, equipment and vehicles as well as limiting access to non-essential workers and visitors.
Talking about the lockdown, the UK’s four chief veterinary officer, said that the decision had not been taken lightly.
In a joint statement, they said: “Taking this action now is the best way to protect birds from this highly infectious disease.”
The virus is brought in by wild birds migrating from other parts of Europe and Russia.
They added that the new housing measures will be kept under regular review.
