The Japanese government has ordered the cull of a further 770,000 birds after avian flu was detected at a farm in northern Japan, according to Dow Jones.

Officials said the H5 virus strain had been detected among chickens at Moriya farm in the Ibaraki prefecture, which is around 65 miles north of Tokyo.

Hundreds of thousands of birds have already been culled in the same region during the past few months because of outbreaks of the H5N2 virus.

Officials do not know yet whether the most recent cases are H5N2 or the H5N1 strain that has been responsible for 79 human deaths in Asia and Turkey since 2003.