Russian veterinary officials have closed down a popular pet market in Moscow after the recent outbreaks of the deadly bird flu were all traced back to the market.
The five outbreaks, which have killed two dozen birds in different villages outside of the city, have been linked to birds bought in the past two weeks at the capital's Sadovod market or "Ptichka" ("Birdie") market.
The head of Russia's veterinary surveillance, Nikolai Vlasov, says laboratory tests have confirmed that the H5N1 bird flu virus in all five cases was highly pathogenic and potentially dangerous to humans, and is probably related to the Asian strain of the virus.
This is Russia's second outbreak this year and the closest to Moscow ever recorded.
Experts suspect the virus was probably brought to Moscow by migrating birds from the Caucasus or the Middle East.
In January the H5N1 strain killed poultry in three settlements in the southern region of Krasnodar but to date no human cases of bird flu have ever been recorded in Russia.
The virus remains predominantly a disease of birds and is difficult for humans to catch.
It has nonetheless killed 167 people worldwide since 2003, mainly in Asia and in almost all cases the victims had been in direct contact with infected birds.
According to the World Health Organisation (WHO) a total of 273 cases have been recorded in humans to date worldwide.
Health experts are concerned the virus could mutate into a form that passes easily from human to human, triggering a global pandemic with the potential to kill millions.
In neighbouring Azerbaijan five people out of a total of eight cases have died from the lethal bird flu virus.
Vlasov says restrictions are in place limiting movement to and from the five villages where the bird flu was found, and the Sadovod market remains closed and patrolled by armed guards until further checks are conducted.