Restrictions have been put in place around a farm in Suffolk amid concerns over a new outbreak of bird flu, the Government has said.
Lab tests have confirmed avian flu strain H5N8, which has been circulating in wild bird populations and caused a number of outbreaks in the UK, but it is not yet clear whether the disease is "highly pathogenic" - deadly to birds - or not.
The affected poultry farm near Redgrave, Mid Suffolk, contains around 23,000 birds, a number of which have died.
A decision has been made to humanely cull the remaining birds, while an initial 10km (six mile) control zone has been put in place to prevent spread of the disease.
Officials said further investigations were continuing to establish if the disease was highly pathogenic and find the possible source of the infection.
Public Health England said the risk to public health from the virus was very low and the Food Standards Agency said it does not pose a food safety risk for consumers.