Nov. 13 (Bloomberg) -- The bird flu virus found at a poultry farm is the deadly H5N1 strain, U.K. officials confirmed today.

The source of the infection at the farm, home to 5,000 turkeys, more than 1,000 ducks and almost 500 geese, is under investigation, the Department for Environment Food and Rural Affairs said today at a press conference broadcast on the BBC.

``Culling of the birds on the site is now under way,'' acting Chief Veterinary Officer Fred Landeg said at the press conference. ``We do not yet know the source of the outbreak.''

A 3-kilometer (2-mile) protection zone and a 10-kilometer surveillance zone are being set up around the infected farm, Defra said. A wider restricted zone covers the whole county of Suffolk and most of neighboring Norfolk. Within the zones, the movement of poultry will be limited and all birds must be housed or isolated from contact with wild fowl, the agency said.

U.K. authorities have banned bird shows and pigeon racing and urged poultry keepers to report any suspected disease.

The H5N1 strain of avian influenza has killed more than 200 people in a dozen countries since 2003, according to the World Health Organization in Geneva. The virus in fowl has spread from Asia to Africa and Europe.

Britain reported its first outbreak of H5N1 in birds in February at a farm in Holton, Suffolk, operated by Bernard Matthews Holdings Ltd., Europe's largest poultry producer. More than 150,000 turkeys were killed to control the virus.

To contact the reporter on this story: Kristen Hallam in London at khallam@bloomberg.net

Last Updated: November 13, 2007 11:57 EST