A lawyer representing a group of Russian soldiers who were said to have refused to be deployed secretly to Syria says authorities have warned his clients that they could face treason charges.

Counsel Ivan Pavlov told RFE/RL on September 20 that Russian Federal Security Service (FSB) officers are currently interrogating his clients, a group of volunteer Russian Army soldiers serving in the city of Novorossiisk, and are threatening to prosecute them on various charges, including high treason.

The FSB became involved at the request of military prosecutors, who rejected a complaint filed by the soldiers in which the troops argued that such a deployment would be a violation of their rights, Pavlov said.

The lawyer said authorities began efforts to return them to their initial units after media reports last week disclosed the dispute.

The lawyer said the soldiers were only informed at the last moment that their deployment would be to Syria and there were no official papers or orders indicating that as the destination.

Pavlov said soldiers in the Russian Army continue being treated as "cannon fodder" by their commanders.

"They must follow orders, of course, but any order must be clear and legal, so that they could make sure for themselves if the war is theirs or not," Pavlov said. "If people are sent somewhere without knowing their final destination, and at the very last moment these people start realizing that they are being sent to a war zone outside Russia, that surely violates the contract and the legislation."

Pavlov declined to give any details that would identify his clients, saying such information might affect their safety.

Russia's military uses both compulsory and volunteer troops.

Pavlov said that official papers to prove that soldiers have been deployed abroad are the only way to ensure the payment of compensation and other benefits due upon the completion of such services.

"If they never returned from [deployment abroad]," he said, "their relatives would never be able to receive not only compensation but even proof that their relative had died fulfilling his military duty."

In May, President Vladimir Putin signed a decree making the death of Russian troops in "special operations" in peacetime a state secret.

Putin's decree came amid reports of secret burials of Russian soldiers allegedly killed in clashes with Ukrainian armed forces in eastern Ukraine.

Moscow has denied any direct involvement into the Ukrainian conflict but has acknowledged that Russian citizens might be volunteering to fight there.

Ukraine announced earlier this year that it had captured two active Russian servicemen who were fighting Kyiv’s forces in the Luhansk region of eastern Ukraine, and NATO and other Western officials claim evidence has mounted of such Russian troops' presence.

The two men have said they were conducting a reconnaissance mission for the Russian military at the time of their capture, although Moscow claims they were not on active duty at the time.