Two more poultry farms in Norfolk have become infected with bird flu.
The British Department for Environment, Food and Rural Affairs said that preliminary results indicated the farms were affected by the less serious H7N3 strain of avian flu, but that further tests were being carried out by the Veterinary Laboratories Agency.
A spokesman said: "The two free range flocks will be slaughtered on suspicion of an avian notifiable disease.
"A restricted zone has been put in place extending 1km from each of the infected premises.
"The State Veterinary Service is tracing movements and contacts, the necessary surveillance and all appropriate worker protection measures have been put in place."
The 35,000 chickens at the centre of the first bird flu outbreak will all have been slaughtered by tonight.
Meanwhile officials today continued to reassure the public of the "extremely low" risk to human health after a poultry worker at the first farm affected contracted the virus in the form of conjunctivitis.
Today a source at Witford Lodge Farm in Hockering said they expected to complete the cull by tonight and that tomorrow would be spent disinfecting the premises.
A Heath Protection Agency spokeswoman said that no other poultry workers at the farm had shown symptoms of illness caused by H7 avian flu. The worker is thought to have become infected via close contact with poultry. The HPA said he reported his illness on Thursday, adding that symptoms were limited to an eye infection, without respiratory problems.
The infected man, who has not been identified, has the low pathogenic H7N3 strain of avian flu which does not transmit easily from person to person, the HPA said.
A Defra spokeswoman said she was not in a position to identify the two new farms that have tested positive for avian flu. However, she said that they belonged to the same owner and were not owned by Banham Poultry, which owns Witford Lodge Farm at Hockering, where H7N3 has been confirmed
The spokeswoman said that one farm had 7,500 chickens and the other had 7,800 chickens. They will now be slaughtered and a 1km restriction zone put in place.
PA