New outbreaks of highly pathogenic avian influenza have been confirmed at two turkey farms in Norfolk.
Defra confirmed on the weekend H5N8 bird flu cases in rearing turkeys at two separate farms, one near King's Lynn and the other in West Norfolk.
A 3km Protection and 10km Surveillance Zone has been put in place around the infected premises.
The county saw its first outbreak of avian influenza on Friday 4 December, at a premises near Attleborough, Breckland.
It comes as the government announced new mandatory housing measures to commence from 14 December as UK bird flu cases mount.
It will be a legal requirement for all farmers and keepers to keep their birds indoors and to follow strict biosecurity measures
Just last week, two cases were recorded at turkey farms near Northallerton, North Yorkshire.
A joint statement from Britain’s three Chief Veterinary Officers said: "We have taken swift action to limit the spread of the disease and are now planning to introduce a legal requirement for all poultry and captive bird keepers to keep their birds housed or otherwise separate from wild birds.
"Whether you keep just a few birds or thousands, from 14 December onwards you will be legally required to keep your birds indoors, or take appropriate steps to keep them separate from wild birds.
"We have not taken this decision lightly, but it is the best way to protect your birds from this highly infectious disease."
How many cases of bird flu have there been?
The introduction of new measures follows a number of confirmed cases of avian influenza in the UK:
• H5N2 (low pathogenic) avian influenza confirmed at a site near Deal in Kent on 2 November
• H5N8 (highly pathogenic) avian influenza confirmed at a site near Frodsham in Cheshire on 2 November
• H5N8 (highly pathogenic) avian influenza confirmed at a broiler breeder farm near Leominster in Herefordshire on 10 November
• H5N8 (highly pathogenic) avian influenza was confirmed at a site near Stroud in Gloucestershire on 19 November
• H5N8 (highly pathogenic) confirmed at a premises near Melton Mowbray in Leicestershire on 21 November
• H5N8 (highly pathogenic) influenza confirmed at two premises near Northallerton, North Yorkshire on 29 November and 1 December
• H5N8 (highly pathogenic) influenza confirmed at a premises near Attleborough, Breckland, Norfolk on 4 December
• H5N8 (highly pathogenic) influenza confirmed at a premises near King’s Lynn and West Norfolk on 5 December