LONDON (AP) — British authorities said Monday that all poultry and other captive birds in England must be kept indoors from next week after bird flu was detected in dozens of farms across the country, as well as in wild birds.

The U.K. is facing its worst ever outbreak of avian influenza, with over 200 cases confirmed since October 2021 and millions of birds culled.

The mandatory measures, which come into force on Nov. 7, legally require all bird keepers to follow strict biosecurity rules to protect their birds, whether pets, commercial farm poultry or just a few birds in a backyard.

“We are now facing this year the largest ever outbreak of bird flu and are seeing rapid escalation in the number of cases on commercial farms and in backyard birds across England," the U.K.'s chief veterinary officer, Christine Middlemiss, said in a statement.

“The risk of kept birds being exposed to disease has reached a point where it is now necessary for all birds to be housed until further notice,” she added.

The measures were already in force since late September in areas including Suffolk and Norfolk in eastern England.

Authorities say the risk to public health from the virus remains very low.

But the outbreak has led to concerns about the supply of turkeys for the Christmas season. Earlier this week, the Department for Environment, Food and Rural Affairs announced that turkey, geese or duck farmers can slaughter their flocks early, freeze then defrost them to be sold for Christmas to help ease the impact of the outbreak on their businesses.