Officials in the Arctic town of Vadso, part of Norway's Finnmark county, said they had collected more than 10,000 dead birds in the area and the Norwegian Food Safety Authority on Thursday imposed a travel ban covering three nature reserves.
"The outbreaks we are seeing in various places in Finnmark this year are much larger than we have seen in the past in Norway," said Ole-Herman Tronerud, the chief veterinary officer at the Norwegian Food Safety authority.
The H5N1 virus strain has spread among poultry and wild birds for years but there have been sporadic outbreaks reported globally in mammals such as cats, mink and otters.
Neighbouring Finland also said wild birds were heavily affected and that the H5N1 strain has now been found in 20 fur farms, up from 12 earlier this week.
"The pathogen was confirmed as a variant circulating especially among the seagulls," Finland's ministry of social affairs and health said in a statement on Wednesday.
Three UN agencies this month warned that outbreaks globally raised concerns that the virus might adapt to infect humans more easily, and urged countries to strengthen disease surveillance and improve hygiene at poultry farms.
The World Health Organization has said that the risk to humans from H5N1 remains low, but said reports of infections in mammals needed to be monitored closely.
Source: Reuters