Four Russian soldiers have been killed in fighting in eastern Syria, Russia's Defense Ministry said, although a war monitor said the death toll was believed to be twice as high.
The Russian Defense Ministry said in a statement on May 27 that four Russian servicemen were killed in the eastern province of Deir Ezzor when "several mobile terrorist groups attacked Syrian government artillery at night."
The statement added that two Russian military advisers were killed on the spot. Five other personnel were injured and taken to a Russian military hospital. Two of them died from their wounds.
The ministry also said that 43 militants were killed in the same fighting.
The statement did not say exactly when or where the fighting occurred, although a war monitor said it may have taken place on May 23.
Russia's death toll was disputed by the Syrian Observatory for Human Rights, which said nine Russian soldiers were killed on May 23 alongside at least 26 Syrian government soldiers in an attack in Deir Ezzor by Islamic State (IS) militants.
Rami Abdel Rahman, the head of the London-based monitoring group, told AFP "several groups" of militants had attacked pro-government forces near the town of Mayadin and that some Russian nationals were with them at the time.
According to AFP, the Russian statement raised the official count of soldiers killed in Syria to 92.
The biggest number of casualties came in March when a transport plane crashed at Syria’s Hmeimim airbase, killing all 39 people on board.
Russia has conducted a bombing campaign in Syria since September 2015, helping reverse the course of the nation's seven-year civil war in Syrian President Bashar al-Assad's favor.
Syrian rebel groups and militant organizations still control parts of northwestern and southwestern Syria, while a Kurdish-led alliance backed by the United States holds most of the northeast.