LONDON (AFP) - An outbreak of the H7 strain of bird flu at a farm in central England is "highly pathogenic," officials said Wednesday.

All the chickens on the farm have been slaughtered following detection of the virus, which does not pose a high risk to humans, at the farm in Banbury, Oxfordshire late Tuesday.

"The Chief Veterinary Officer has confirmed that the strain of H7 avian influenza present in laying hens at the farm in Banbury is highly pathogenic," the Department for Environment, Food and Rural Affairs said in statement.

Highly pathogenic means that the virus has a relatively high ability to produce disease.

Japan announced that it was suspending imports of poultry from Britain following the outbreak.

Officials near the affected farm have introduced measures meaning poultry within three kilometres (1.9 miles) of the farm must be isolated from wild birds and bird gatherings and movement of birds are banned within 10 kilometres.

The farmer at the centre of the recent outbreak said in a statement distributed by the National Farmers´ Union that it had been a "devastating" 24 hours.

"The source of the disease is not yet known and all birds on the farm will be or are being culled to help contain and eradicate this disease," the farmer, who was not identified, said in the statement.

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

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

The H5N1 virus can cause human deaths and was most recently detected in Dorset in January.