The United Kingdom government says all poultry and captive birds in England will legally be required to be kept indoors from November 7 as part of measures to tackle the country's largest-ever outbreak of avian flu.

The mandatory housing order will extend measures already in force in parts of eastern England to the whole region following an increase in the risk of bird flu in wild birds to "very high," the government said in a statement.

Bird keepers will also be required to follow stringent biosecurity measures including disinfecting clothing, footwear, equipment and vehicles and keeping mortality records.

"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," UK Chief Veterinary Officer Christine Middlemiss said.

"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."

In the same statement, the UK Health Security Agency said it continued to advise that the risk to public health from the virus was very low.