LONDON (AFP) - Vets ordered the slaughter of some 5,000 birds Monday after an outbreak of avian flu on a farm in eastern England, officials said.

The outbreak -- of the H5 strain of the virus and not necessarily the lethal Asian type -- was found on a farm near the town of Diss, said a spokesman for the Department for Environment, Food and Rural Affairs (Defra).

A 1.8-mile radius protection zone and a 10-kilometre surveillance zone were imposed around the farm.

"It is H5 but we don´t know which strain," the spokesman told AFP, saying further tests were being carried out to find out if it was the H5N1 lethal strain.

All birds on the farm involved, including turkeys, ducks and geese, will be slaughtered, he added.

The outbreak involves the first cases of the disease in Britain since May, when a child became infected with a low-risk strain of bird flu in Wales.

"Everybody needs to be concerned. This is avian influenza. We are asking every poultry keeper to be vigilant," veterinary chief Fred Landeg told Sky News television.