Poultry farms around the capital were under tight control after animal and plant health watchdog Rosselkhoznadzor said at the end of last week that several birds died from the virus in villages around Moscow.
"Laboratory tests confirmed that H5N1 bird flu found in five regions around Moscow was highly pathogenic and potentially dangerous for humans, and is probably related to the Asian type of the virus," Nikolai Vlasov, a senior Rosselkhoznadzor official, told Itar-Tass news agency.
No human cases of bird flu have been recorded in Russia.
The outbreak is Russia's second this year and the first ever recorded close to the capital. The highly pathogenic H5N1 strain killed poultry in three settlements in the southern region of Krasnodar last month.
Vlasov told the agency the virus could have been brought to Moscow by wild birds migrating from the Caucasus, Balkans or Asian regions.
The H5N1 strain of bird flu has killed 167 people worldwide since 2003, mostly in Asia. Many of the victims had been in direct contact with infected birds.