Millions of free-range hens and other birds will have to be kept indoors from 14 December, in a national government crackdown to try to limit the spread of a virulent strain of avian flu across Great Britain. The Department for Environment, Food & Rural Affairs (Defra) said in a statement that the chief vets of England, Scotland and Wales had agreed the new legal requirement for all birdkeepers to bring their flocks indoors, to keep them separate from potentially infectious wild birds. The strict new lockdown-style measures, which have already been introduced in the Netherlands, apply not only to large commercial poultry farms but also smaller keepers with hens in coops or garden pens. Keepers are being urged to use the next 11 days to prepare for the new measures, including taking steps to safeguard animal welfare, consult their vet and where necessary erect additional housing or self-contained netted areas. Eggs can continue to be marketed and labelled as “free-range” for 16 weeks after the birds have been brought indoors, but if the restrictions last beyond that they must be downgraded to “barn produced” using stickers on packaging. Similarly, poultry meat can be labelled free-range for 12 weeks. To be defined as free range in the UK, a chicken must normally be at least 56 days old before slaughter and have had access to outside space for at least half that time. Premium free-range eggs currently represent 56% of UK retail egg sales – the highest proportion of any European country – whereas just 2% of eggs are from the barn system. Aimee Mahony, chief poultry adviser with the National Farmers’ Union, urged all farmers to comply with the new rules. “Due to a number of confirmed avian influenza cases, the introduction of these new housing measures is a logical next step to best protect poultry. These new measures mean that every poultry keeper, whether you have one hen in the garden or a large poultry business, must house their birds indoors and I would urge everyone with poultry to take these measures seriously. It’s crucial that everyone remains vigilant and reports any signs of disease in their birds at the earliest opportunity.” On Sunday, all 10,500 turkeys at a farm in Northallerton, North Yorkshire, were culled after an outbreak was spotted on Saturday, while a 3km (2-mile) and 10km temporary control zone was put in place to stop the disease spreading. About 13,500 birds were culled earlier this month following confirmation of an avian flu outbreak at a commercial farm in Helsby, near Frodsham in Cheshire. Defra reiterated that the risk to human health and food safety from the virus was “very low”. UK and European farmers have been on alert after outbreaks of highly pathogenic avian influenza among wild and domestic birds in western Russia and Kazakhstan. Wild birds migrating from mainland Europe during the winter period can spread the disease to poultry and other captive birds. In a joint statement, Great Britain’s three chief vets said: “We have taken swift action to limit the spread of the disease and are now planning to introduce a legal requirement for bird keepers to keep their birds housed or otherwise separate from wild birds. We have not taken this decision lightly, but it is the best way to protect your birds from this highly infectious disease.” A spokesman for the British Egg Industry Council said: “To date there have been no cases of avian flu in free-range laying flocks; however it is vital that we continue to protect the health and welfare of the UK’s laying flock and commercial poultry operations. The requirement to keep birds inside from 14 December is a further step to those already taken to continue to protect flocks.” It is the first time in four years that a so-called housing order has been imposed on the UK poultry sector due to a significant outbreak of bird flu, when measures were put in place from December 2016 to May 2017. A spokesman for Compassion in World Farming said: “We understand the reasons for bringing poultry indoors, but would urge that the period be kept as short as possible and that steps are taken to ensure the welfare of birds temporarily confined indoors.”