AP cited Aleksei Alekseyenko, spokesman for the federal agricultural oversight agency Rosselkhoznadzor, as saying that four separate incidents of birds dying could be traced to single market located outside the city.
The market in question has been closed as investigators try to determine where it obtained the birds it was selling.
The news came a day after tests confirmed the presence of the deadly H5N1 strain of the virus in the Domodedovo and Odinstsovo districts of suburban Moscow.
All the birds at the farms had been killed, officials said today. "We are taking all necessary measures," said Nikolai Vlasov, director of veterinary inspection for Rosselkhoznadzor.
Dozens of bird deaths reported on February 17 in the Podolsk District were still under investigation
Elsewhere today, reports of new cases of dead birds surfaced. Moscow Oblast's chief veterinarian, Olga Gavrilenko, was quoted as telling Ekho Moskvy radio that dead domestic birds had been reported in the city's Taldom District. Russian news agencies reported cases in the Naro-Fominsk District.
Bird flu has not been verified as the cause of death in the newest reported cases.
Last year, a number of bird-flu cases were recorded in Russia, but none close to the Russian capital. Prior to the latest outbreak, one case had been registered in Krasnodar Krai in 2007.
(AP, dpa, AFP)