Two now-retired agents in the General Directorate for External Security (DGSE), France's foreign intelligence agency, as well as the spouse of one of them, were charged in December, but the case was revealed for the first time late on Thursday.
The revelations came just a few weeks after US authorities said they had indicted a former Central Intelligence Agency operative on charges of spying for China, following his arrest in January.
France's domestic intelligence service, the General Directorate for Internal Security, first discovered the suspected double agents, before alerting the defence ministry, which began its own investigations.
In a statement, the DGSE -- similar to Britain's MI6 or the United States's CIA -- said the revelations "are a major area of focus for the DGSE as well all French counter-intelligence services."
"We are being extremely vigilant in this matter," Parly told CNews.
The three people were charged on December 22, 2017, and two have been detained since then, the judicial source told AFP.
On Thursday, France's Quotidien television programme and Le Monde newspaper reported that four people were suspected of having been recruited by the Chinese authorities to spy on French foreign intelligence operations.
The defence ministry has refused to comment on the reports.