A Russian warplane this weekend flew over a French warship at low altitude in the eastern Mediterranean, a deliberate breach of international regulations, a French naval source said on Tuesday.
The incident, first reported by Le Point magazine, comes as tensions mount between Russia and Western nations following a suspected chemical weapons attack in Syria on April 7. At least 60 people were killed in the attack, according to a Syrian relief agency.
France, the United States and their allies are considering a coordinated military response after accusing the Russia-backed Syrian government of being behind the attack. Damascus and Moscow have denied a chemical attack took place.
The weekly magazine said the Russian plane had flown over frigate Aquitaine over the weekend and was fully-armed.
The Aquitaine is equipped with 16 cruise missiles and 16 surface-to-air missiles. It is currently operating off Lebanese shores alongside US ships as part of France's contingent fighting Islamic State militants in Syria and Iraq.
"The flight took place several days ago," a French naval source said, adding that France had contacted Russian authorities over the matter.
"Passes by military aircraft over warships are things that happen at sea. When it is deemed too close, the opposing party is notified," the source said.
The Russian air force has already carried out such "aggressive" flights over Western warships in the past.
In April 2016 two Russian warplanes flew simulated attack passes near a US guided missile destroyer in the Baltic Sea, so low they created wake in the water.
Phone calls to the Russian defense ministry in Moscow were not answered after business hours on Tuesday.