Russia's defence ministry said on Tuesday that one if its military aircraft with 14 people on board disappeared from radar screens over Syria at the same time that Israeli and French forces were mounting aerial attacks on targets in Syria.
A US official said Washington believed the aircraft, which is an Il-20 turbo-prop plane used for electronic reconnaissance, was inadvertently shot down by anti-aircraft artillery operated by Moscow's ally, the Syrian government.
Around the time the plane disappeared, the Syrian coastal city of Latakia -- near a Russian airbase to which the Il-20 was returning -- came under attack from "enemy missiles" and missile defence batteries responded, Syrian state media reported.
The defence ministry in Moscow said the aircraft was returning to the Russian-run Hmeymim airbase in Latakia province when, at about 11:00pm Moscow time (20:00 GMT), it disappeared from radar screens.
The plane was over the Mediterranean Sea about 35 km (20 miles) from the Syrian coastline, Russia's TASS news agency quoted the ministry as saying in a statement.
"The trace of the Il-20 on flight control radars disappeared during an attack by four Israeli F-16 jets on Syrian facilities in Latakia province," the statement was quoted as saying.
"At the same time Russian air control radar systems detected rocket launches from the French frigate Auvergne which was located in that region."
The fate of the 14 people on board the missing plane is unknown, and a rescue operation has been organised out of the Hmeymim base, the ministry said.
