Health officials in Britain said Thursday they had identified a rare case of avian flu in a person, as the country battles its largest-ever outbreak of the virus among birds.

Transmission of avian flu from bird to human is very rare and has previously only occurred a small number of times in Britain, the UK Health Security Agency (UKHSA) said.

The infected individual, in southwest England, was said to be "well" and was self-isolating, it added.

"The person acquired the infection from very close, regular contact with a large number of infected birds, which they kept in and around their home over a prolonged period of time," the UKHSA said in a statement.

"All contacts of the individual, including those who visited the premises, have been traced and there is no evidence of onward spread of the infection to anyone else."

The agency noted the risk to the wider public from avian flu remained "very low" but cautioned people not to touch sick or dead birds.

Britain culled around half a million birds in 2021 as it grappled with what Environment Secretary George Eustice has called the country's "largest-ever" avian flu outbreak.

Alongside culling, the government rolled out new rules in December requiring keepers to ensure all captive birds are indoors and follow strict biosecurity measures to try to stem the spread of the virus.

However, officials have voiced concerns that wild birds migrating from mainland Europe during the winter months may be carrying the disease.

Geese, ducks and swans are among the wild bird species known to have been affected, while a number of birds of prey are also confirmed to have died.