The agency, quoting a well-informed source in the Federal Counterintelligence Service, said Sintsov, who was arrested in January, had held a high post in an arms concern.
The source said he had passed over information about Russia's defense capability and defense research projects.
He declined to make any assessment of the damage caused, Interfax said. He would not divulge when Sintsov had been recruited beyond saying it was after 1986.
Itar-Tass, on March 1 disclosed the man's arrest, saying he had been supplied with invisible writing materials and means of supplying information to agents at Moscow's British Embassy.
Itar-Tass said then that the man had admitted his guilt and had been charged with high treason.
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