The officer was detained by the French security agency when he was about to return to Italy
A senior French military officer had been placed under investigation over a suspected breach of security, Armed Forces Minister Florence Parly said on Sunday.
According to Europe 1 radio, a French lieutenant colonel, based in Italy and stationed with NATO, is suspected of having passed sensitive documents to the Russian secret services.
Asked to comment on the report, Parly said the ministry had informed prosecutors about the case. She did not elaborate on what the officer was suspected of having done.
"We have taken all the necessary safeguard measures," she added.
According to Europe 1, the officer was detained by the French security agency when he was about to return to Italy and was remanded in custody at La Santé prison in Paris.
A judicial source said the Paris prosecutor's office had launched an investigation following a report from the Armed Forces Ministry on July 22.
As a result, on Aug. 21 an officer with a posting abroad was indicted for passing information to a foreign power and compromising national security, according to the source, who said the officer was remanded in custody the same day.