A Russian drive to recruit Syrians to fight in Libya for militia leader Khalifa Haftar accelerated in May when hundreds of mercenaries were signed up, Reuters reported five Syrian opposition sources and a regional source familiar with the matter saying.
Private military contractor Wagner Group is conducting the hiring with Russian army supervision, according to two senior Syrian opposition sources and the regional source. A former Wagner Group member said it first sent Syrians to Libya in 2019.
The Russian Defence Ministry and the Wagner group did not respond to questions from Reuters.
Turkey, meanwhile, says it is providing military support to the other side of the conflict, the internationally recognised Government of National Accord (GNA) based in Tripoli.
Turkish President Recep Tayyip Erdogan said in February that fighters from the Turkey-backed Syrian National Army were in Libya, as well as Turkey's own military.
Russia has been a staunch ally of Syrian President Bashar Al-Assad, helping him crush the rebellion at home. Moscow's involvement in Libya is an extension of its ambition to project influence in the Eastern Mediterranean, some experts say.
Egypt and the United Arab Emirates have also lent support to Haftar because they suspect the GNA of having ties to the Muslim Brotherhood.
The involvement of Russia and Turkey on opposite sides of the Libyan conflict has echoes of the war in Syria, where they have also backed warring parties. It also risks exacerbating the conflict, experts have warned.
"Russia and Turkey are both escalating their fire power and force numbers in Libya, where Europe has been caught on its heels," said Joshua Landis, head of the Centre for Middle East Studies at the University of Oklahoma.
"Russia has tried to match Turkey's effort to send Syrian mercenaries, but with mixed results."
Wagner has up to 1,200 people deployed in Libya, according to a confidential UN report seen by Reuters in May. The Russian state has denied having forces in Libya.
When asked in January if the Wagner Group is fighting in Libya, Russian President Vladimir Putin said that if there are Russians in Libya, they are not representing the Russian state, nor are they paid by the state.
A spokesman for Haftar's Libyan National Army denied it had recruited Syrian fighters. It has repeatedly highlighted the presence of Syrians fighting alongside its enemy.
The Syrian government's information ministry did not respond to questions sent via email.
New recruits to the Russian effort in support of Haftar included 300 from the Homs area, among them former Free Syrian Army fighters, according to one of the two senior opposition sources, and some 320 from the southwest, a third source said.
According to the Syrian Observatory for Human Rights, which reports on the Syrian conflict using a network of sources on the ground, more than 900 Syrians were recruited by Russia to fight in Libya in May.