The station reported Monday that judo athlete Cedric Mandembo disappeared after the closing ceremony, and has not been reachable on his mobile phone. He lost his match after 49 seconds.
Authorities tell the radio station that the Congolese athlete left the Olympic village with his baggage without saying where he was going.
The others who have gone missing are two officials with the boxing and judo teams, and a national athletic official.
Already at least seven Cameroonian athletes have failed to return home after the games.
Congo has suffered decades of dictatorship and war and remains mired in poverty despite its mineral riches.