A top Russian human rights body says it has been contacted by Russian soldiers who fear being sent to fight in Syria.
The presidential Human Rights Council told BBC Russian that it was seeking an explanation from the Russian military.
Officers reportedly told some soldiers that they would be sent to fight “in a hot country“. Russia has sent military hardware to Syrian government forces.
Separately, a top Russian security official said nearly 2,400 Russians had joined Islamic State (IS) fighters.
Gen Sergei Smirnov of the Federal Security Service (FSB) did not say where the Russian Islamist militants were fighting. IS controls a big swathe of Syria and Iraq, and part of Libya.
He also said a larger number of volunteers from Central Asia had gone to fight for IS, bringing the total of Russians and Central Asians to more than 5,000.
It is bigger than previous Russian estimates of IS militants from the ex-Soviet Union.
IS has been spreading its influence among Muslim communities in Russia’s North Caucasus, and many of the Russians in its ranks are believed to be Chechens. An anti-Moscow insurgency continues in the region.
The main nationalities of IS volunteers from Central Asia are Uzbek, Kazakh and Turkmen.
According to intelligence estimates, IS has about 20,000 foreign fighters, most of them Arabs. At least 3,400 of the 20,000 are from Western Europe.
On Tuesday, Russian President Vladimir Putin pledged continued military support for Syria’s Bashar al-Assad, whose forces are fighting IS and other rebel groups.
The US expressed concern over a Russian military build-up near Syria’s coastal city of Latakia, monitored by US intelligence.
The US says Russia is building an airbase there, but it is not clear whether any Russian troops are directly involved in the Syrian fighting.
Syrian Foreign Minister Walid Muallem, quoted by Russia’s Tass news agency, said “there is no joint fighting on the ground with Russian troops”, but he did not rule out requesting that if necessary.
“So far the Syrian army is able (on its own) and what we need frankly is more of the ammunition and quality weapons,” he said.
Sergei Krivenko of the Russian Human Rights Council said he had received worried messages from Russian soldiers and their relatives, who feared they could be sent to Syria.
Any secret deployment of troops to Syria would be illegal, he said.
The council is an advisory body whose role is to assist the Kremlin in safeguarding human rights.
President Putin has legal authority to send troops to Syria, Mr Krivenko said, but he would have to sign a decree to that effect, which must be made public.
Kremlin spokesman Dmitry Peskov said he was unaware of any such messages about Syria having been sent by Russian soldiers.
On Friday the Russian news daily Gazeta.ru reported that Russian professional soldiers and military hardware were being shipped to Syria clandestinely from the Black Sea port of Novorossiysk.
Identification plates were removed from military vehicles, it said.
Soldiers interviewed by the paper said they did not find out about their mission until they arrived in the port. Officers told them only that they were going “to a hot country”.
Some soldiers had assumed they were being sent to Donbas in eastern Ukraine, where pro-Russian separatists are resisting the Ukrainian army.
A soldier called Alexei said that “so far our command has not specified where we are going… Our regiment has lots of companies, and we were told they had picked out the best 20 fighters.
“But nearly all are unhappy and not prepared to go to Syria,” he said.
Source: BBC News