The H5 strain of bird flu has been confirmed in turkeys on a farm on the Norfolk-Suffolk border, the Department for Environment, Food and Rural Affairs has announced.

Around 5,000 birds are being slaughtered at the farm near Diss, which has ducks and geese as well as turkeys, and 3km protection and 10km surveillance zones have been set up around the premises.

Deputy chief veterinary officer Fred Landeg said the cause of the infection was not known at the moment and he urged all poultry farmers to remain vigilant.

He said: "Everybody needs to be concerned, this is avian influenza.

"We are asking every poultry keeper to be vigilant, to house their birds where they are required to do so in any restricted area and carry out good bio-security measures and report any signs of disease."

Dr Landeg stressed that the epidemiological investigation into the outbreak, which is at a rearing unit, would try to establish its origin but that it was still at a very early stage.

Officers from the Animal Health agency will be visiting the farms within the protection zone to inspect their birds and see if they are also affected, he said.

Dr Landeg played down the likelihood of a link to the outbreak in February this year at a Bernard Matthews' plant in Holton, Suffolk.

He said: "There was a case on another premises in this area, a large turkey producer in February of this year.

"At this stage we can't (draw any conclusions from the proximity). We think that this is a new introduction onto this premises and we will be looking at any possible links to establish where it may have come from and where it might have spread to."

He also reassured the public that they were not at risk of infection from eating poultry meat and eggs as long as they were cooked properly.

He said: "It is very difficult to transmit avian influenza from birds to human beings. There has to be fairly close contact with the birds and with their faeces.

"I think we should also reassure everybody that if poultry and eggs are properly cooked, the Food Standards Agency says there is no risk to public health."

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