Avian flu has been confirmed in chickens and geese at a farm in south Norfolk.
The UK's deputy chief veterinary officer said the H5N8 strain had infected around 35 birds at a farm near Diss.
A number of the birds have died and the remaining are to be culled.
A full investigation is under way to find the source of the infection. The risk to the public is said to be low.
The exact location of the outbreak has not been revealed.
But a 3km protection zone and 10km surveillance zone have been put in place around the infected premises.
In February this year, around 23,000 chickens were destroyed at Bridge Farm in Redgrave on the Suffolk and Norfolk border after an outbreak of H5N8 avian influenza virus.