The strain of bird flu discovered at a Bernard Matthews farm in Suffolk is 99.96% genetically identical to the strain found in Hungary, scientists have said.

The discovery follows preliminary tests carried out last week which found the viruses in Suffolk and Hungary, where Bernard Matthews has a number of operations, “may well be identical”.

“The comparison between the UK and Hungarian viruses reveals a high level of genetic match which can not be said of other European virus strains,” said Ian Brown, chief avian virologist at the Veterinary Laboratory Agency.

Deputy chief vet Fred Landeg added: “The current working hypothesis is that poultry-to-poultry transmission is the most likely source of the outbreak. However, I must reiterate that we are not discounting any line of inquiry.”

Officials have been investigating imported meat from Hungary at the Suffolk site, including information about the dates and amounts of poultry imported, the route followed and whether it complied with EU health requirements.

Meanwhile, production re-started at the site yesterday after Bernard Matthews received the go-ahead from the Meat Hygiene Service.