Norwich Livestock Market has cancelled Saturday's sheep sale after three more cases of the dangerous bluetongue virus prompted an extension of animal movement restrictions.
Defra has found three infected sheep on two farms near Norwich and Lowestoft - adding to the initial case near the Broads village of Haddiscoe, which became the UK's first case of the summer earlier this week.
It marks a worrying return of the potentially-fatal animal virus, which prompted weeks of livestock movement restrictions last winter after dozens of cases were found in Norfolk and Suffolk.
Following the new cases of bluetongue serotype 3 (BTV-3), Defra says all three animals will be "humanely culled to minimise the risk of onward transmission".
And the 20km temporary control zone (TCZ) initially centred on Haddiscoe has been extended to cover an area stretching from Watton to Southwold.
The zone enforces restrictions "to all ruminants and camelids and to their germinal products", with licences required to move into or within the zone.
Norwich Livestock Market chairman Stephen Lutkin said the restrictions had forced the cancellation of the sheep sale at Hall Road on Saturday - but the fortnightly cattle sale is expected to go ahead.
He said: "The main reason for that is that the majority of sheep buyers are in the clean zone, so if they came to Norwich they would not be able to buy anything. And the disease at the moment seems to be most prevalent in sheep.
"We can sell cattle from inside the zone and outside the zone, although they all now have to come under licences. The only thing is that anything from outside coming into Norwich would then not be able to leave the zone. So there would have to be buyers within the zone.
"With the cattle, the majority of the buyers are already in the zone, so that is where we took the decision to carry on with the cattle, but there will be no sheep sale on Saturday."
The virus is spread by biting midges, which are more active in warm weather and are believed to have blown across the sea from mainland Europe, where the virus has been circulating rapidly.
Free testing is available for animals moving from the highest-risk coastal counties of Norfolk, Suffolk, Essex, Kent and East Sussex, to help guard against transporting undetected disease to new areas. Defra says priority will be given to testing within the temporary control zone.
Bluetongue does not affect human health or food safety, but it is a notifiable disease and livestock keepers must report suspected cases to the APHA on 03000 200 301.
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