The new outbreak occurs one month after the UK regained its status on 6 October from the World Organisation for Animal Health (OIE) as a country free of notifiable avian influenza.
Over the past six months the UK has also been battling re-occuring outbreaks of foot-and-mouth disease, and bluetongue, raising fresh questions about the safety of its meat supply -- and the continued health of its export market.
The outbreak, at a turkey farm on the Norfolk and Suffolk border area, as confirmed yesterday by the Department for Environment, Food and Rural Affairs (Defra).
All 5,000 birds on the premises will be slaughtered, Defra stated. Investigations are underway to determine whether or not the outbreak is due to H5N1 and whether the strain is high or low pathogenic.
A 3km protection zone and a 10km surveillance area have been established around the infected farm. Investigations are also underway to determine if the disease has spread to other areas.
The Food Standards Agency has repeated its advice that properly cooked poultry and poultry products, including eggs, are safe to eat.
In February, an outbreak H5N1 virus on a Suffolk farm, owned by Bernard Matthews, killed some 2,600 birds with another 159,000 being slaughtered.
The strain was linked to an almost identical strain found in an outbreak in Hungary in January.
A report into the UK's handling of the outbreak, published by Defra on 11 October, found that the regulatory response to the outbreak was "effective" and highlights the benefits of the contingency planning.
The report also made 34 detailed operational recommendations on the management of an outbreak of avian influenza, or other exotic animal disease.
The recommendations were all been accepted and have been adopted in the current regulatory response to the current foot-and-mouth disease and bluetongue outbreaks in farm animals, Defra stated.
Commenting on the report, deputy chief veterinary officer Fred Landeg said recent bird flu outbreaks in the Czech Republic, Germany and France demonstrate the threat to UK is continuing and real.
As part of the recommendations, Defra and the FSA also jointly commissioned an independent review of the role and responsibilities of the Meat Hygiene Service during animal disease outbreaks.
The review concluded that the arrangements had worked well, but that there were lessons to be learned around clarifying roles and responsibilities for designation of slaughterhouses and enforcement activities.