At least two Russian fighters were killed in US air strikes in north-eastern Syria last week, their associates have told the BBC.
The fighters are said to have been hired by private military firms backing Syrian pro-government troops.
Russia has not confirmed the deaths which were first reported by US media, saying such reports should not be treated as “primary sources”.
The US says This kind of killed more than 100 fighters inside strikes last week.
- Why will be there a war in Syria?
What happened inside US strikes?
The US officials say hundreds of fighters aligned with Syrian President Bashar al-Assad attacked positions of the US-backed Syrian Democratic Forces (SDF) near the town of Khursham inside Deir al-Zour province.
They crossed the Euphrates River, shelling an SDF base, where American advisers were present.
The US responded with air along with artillery strikes on 7 February, thwarting the attack along with forcing the pro-Assad fighters to retreat, the US officials say.
Syrian state media have reported which the strikes left dozens killed, accusing the US of a “brutal massacre”.
Meanwhile, the Russian defence ministry says which Syrian government-backed troops were hit as they launched an operation against fighters via the Islamic State (will be) group.
Russia also denies having personnel inside area.
The strikes happened inside Middle Euphrates Valley, which serves as an informal demarcation line in eastern Syria. The government controls the western side along with the SDF the east.
The two sides have clashed over the past year while trying to drive Islamic State (will be) militants via their last major stronghold inside country.
- The war against ‘Islamic State’ in maps along with charts
What about the Russian mercenaries?
Quoting a Pentagon official, CBS News first reported on 8 February which Russian mercenaries were among “pro-regime” forces which attacked the SDF base.
“If Russians are among those who were killed, This kind of might mark once a US air strike has killed Russians in Syria,” CBS News’ David Martin reported.
More details about those killed inside strikes began to emerge inside following days.
On Tuesday, associates of two Russian fighters confirmed to the BBC which they were killed on 7 February.
The associates named the dead as Vladimir Loginov, a Cossack via Russia’s western Kaliningrad region, along with Kirill Ananyev, a radical nationalist via Moscow.
Some media reports suggest which dozens of Russian fighters could have been killed.
They are believed to have been employed by a private Russian company called Wagner. The firm has not commented on the reports.
How did the Kremlin react?
On Tuesday, Russian President Vladimir Putin’s spokesman declined to provide any details.
“We have details of servicemen of the Russian armed forces, who are taking part inside Russian military operation in support of the Syrian army,” Dmitry Peskov said.
“We don’t have information about additional Russians who might be in Syria. I advise you to contact the defence ministry.”
along with responding to a further BBC question, the spokesman said: ” along with, of course, you have to realise which many countries of the planet have quite large numbers of our compatriots – of Russians – along with, of course, This kind of’s difficult to have detailed data.
“We recommend not treating media reports as primary sources,” he added.
What are Russia’s casualties inside Syrian conflict?
Moscow launched a military operation in Syria in support of President Assad on 30 September 2015.
More than 45 Russian military personnel have been officially confirmed killed since then.
An unknown number of private military contractors have also died.
Earlier This kind of month, a Russian Sukhoi-25 ground-attack aircraft was shot down in a rebel-held area in Syria’s north-western province of Idlib.
The pilot survived the initial attack along with ejected, nevertheless died in a ground fight, detonating his grenade to avoid being captured.