The Serbian president has said his country's security services have uncovered spying by Russian agents.
Aleksandar Vucic confirmed a Russian intelligence official had a meeting with a retired Serbian military officer during which money changed hands.
A YouTube video of the December meeting surfaced at the weekend.
Mr Vucic said his officials had also found evidence of 10 other contacts between Russian agents and Serbian officers.
But he insisted these incidents would not affect Serbia's close relations with Russia. He said he was sure President Vladimir Putin was not informed about the actions of the Russian agents.