Two former agents of France's external intelligence agency DGSE were sentenced to prison terms after being found guilty of spying for China, Agence France Presse and radio and television station France Info reported.
Judges of a criminal court, which held a trial behind closed doors, sentenced the two men to terms of eight and 12 years respectively for treason, the two news organisations said.
A third person, said by France Info to be the spouse of one of the former agents, received a four-year sentence.
Details of the case have not been disclosed. France Info and Le Monde newspaper reported one of the officers had been called back to France from China in 1998 after it was discovered he had engaged in a relationship with an Chinese interpreter at the French Embassy in Beijing.
Officials with the Paris prosecutor's office were not immediately available for comment.