A Russian military aircraft was brought down by a Syrian missile over the Mediterranean Sea, killing all 15 people on board, the Russian defence ministry said.
“The Israeli pilots were using the Russian aircraft as a shield and pushed it into the line of fire of the Syrian defence,” ministry spokesperson Major General Igor Konashenkov said in a statement on Tuesday.
Russia said it would make an “appropriate response” to Israel.
The Russian military said the Il-20 reconnaissance aircraft was hit 35km off the Syrian coast as it was returning to its home base nearby.
An Israeli military spokesperson when asked about both the reported Israeli attack and the Russian plane said: “We don’t comment on foreign reports.”
For several years, Israel and Russia have maintained a special hotline to prevent their air forces from clashing in the skies over Syria.
Israeli military officials have previously praised its effectiveness.
Around the time the plane disappeared, the Syrian coastal city of Latakia – near the Russian Khmeimim airbase to which the Il-20 was returning – came under attack from “enemy missiles”, and missile defence batteries responded, Syrian state media reported.
The Russian military said Israel did not warn it of its operation over Latakia province until one minute before the attack, which did not give the Russian plane enough time to escape.
Al Jazeera’s Rory Challands, reporting from Moscow, said the latest development will test Russia-Israel relations.
“The Russian foreign ministry has summoned the Israeli ambassador Gary Koren so that he can account for what happened,” Challands said.
“This is a reasonably serious development in the Syrian war,” he said.
Moscow has previously lost aircraft during its Syria campaign.
In 2016, a Russian Ministry of Defence Tu-154, carrying 92 people and also on its way to Khmeimim, crashed shortly after taking off from Sochi airport, killing all on board.
In February this year, Syrian rebels shot down a Sukhoi 25 jet over Idlib province.