All birds on the infected farm near Banbury will be slaughtered as a precautionary measure after the case of avian flu was confirmed by new chief veterinary officer Nigel Gibbens.

Testing is continuing to discover whether the strain of bird flu is a highly pathogenic one, Defra said.

Defra said a temporary control zone with an 3km inner zone and a 10km outer zone has been established around the infected premises.

In the inner zone, poultry must be housed and kept isolated from wild birds, and across the whole zone movement of birds and bird gatherings are banned.

The Health Protection Agency said the H7 strain of avian flu was largely a disease of birds and did not transmit easily to humans.

The risk to human health posed from the strain is low, the HPA said.

The Food Standards Agency said the case of bird flu "poses no safety implications for the human food chain".

Dr Judith Hilton, the FSA's head of microbiological safety, said: "Properly cooked poultry and poultry products are safe to eat. The science shows that the virus isn't contracted by eating food, but usually by close contact with infected birds."

This is the fourth case of the H7 strain in the UK, with three outbreaks of the "low pathogenic" or mild version of the virus in Norfolk, North Wales and Merseyside since May 2006.