A Russian military aircraft with 14 people on board has disappeared from radar after flying over Syria, Russia's defence ministry says.
"Connection has been lost with the crew of a Russian Il-20 plane over the Mediterranean Sea," the ministry said.
Contact was lost at about 23:00 local time (20:00 GMT) on Monday, it added.
Russia began military strikes in Syria in 2015 after a request from President Bashar al-Assad, who has stayed in power despite seven years of civil war.
The conflict has so far killed more than 350,000 people.
The incident on Monday reportedly occurred about 35km (22 miles) from the Syrian coast as the Ilyushin Il-20 aircraft was returning to Russia's Hmeimim airbase near the north-western city of Latakia.
"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," Russia's Tass news agency reported.
"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 aircraft and those on board is not yet known. A search and rescue operation is under way, co-ordinated through personnel located at the Hmeimim base, the ministry added.
A French military spokesman told AFP news agency: "The French army denies any involvement in this attack."
Meanwhile, the Israeli military refused to comment on reports its planes targeted facilities in the Latakia area on Monday, saying: "We don't comment on foreign reports."
A US Pentagon spokesman said: "The missiles were not fired by the US military and we have nothing further at this time."
However, an unnamed US official said Washington believed the plane was accidentally shot down with anti-aircraft artillery by the Syrian government.
The Syrian government has not yet commented on the incident.
Hmeimim is Russia's main base for air strikes on rebel groups in Syria - strikes that have enabled President Assad's forces to recover much lost ground in the .
Last year Russia said it had increased security at Hmeimim in response to a foiled drone attack on the base just days after reports that rebel shelling had damaged several planes.
Earlier on Monday Russia and Turkey agreed to create a demilitarised buffer zone in Syria's Idlib province to separate government forces from rebel fighters based there.
Russian President Vladimir Putin said it would be 15km to 25km (9-15 miles) wide and come into force by 15 October.
Courtesy: BBC News