Bird flu has been confirmed on poultry farms near Wells and Cromer - bringing Norfolk's growing epidemic to six cases in the last four weeks.
Animal health teams have identified a highly-pathogenic strain of avian influenza in commercial poultry at sites near Langham and Felbrigg.
Defra said all poultry on the infected sites will be humanely culled, and a 3km protection zone and 10km surveillance zone have been put in place around both premises.
The country is in the grip of its worst-ever bird flu outbreak, with 278 cases across England since October 2021, sparking the culls of more than three million birds.
The pace of the outbreak has slowed since its peak in autumn, when Norfolk recorded more than 40 cases in October alone.
But cases have been on the rise again in recent weeks, as the disease has spread northwards following an outbreak near Taverham on January 10, a Gressingham duck farm near Fakenham on January 4, and two near Diss on December 17 and 30.
Government vets have enforced strict biosecurity measures and a mandatory housing order requiring all captive birds to be kept indoors.
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