Russia said Thursday that close coordination with Turkey and Iran on the ground in Syria continues.
"There has recently been a dangerous increase in tension and a surge of violence in Idlib," the Russian foreign ministry said in a statement on its website.
However, Russia continues to closely coordinate with Turkey and Iran on the ground in Syria, it added.
It also said that a number of Russian and Turkish military specialists had been killed in Syria, without providing any further details.
The ministry said that in mid-January, Russian and Turkish militaries made a new attempt to impose a cease-fire in Syria's Idlib de-escalation zone, but "terrorists ... ramped up their attacks."
"The number of dead and wounded among Syrian servicemen and civilians outside the de-escalation zone has grown into the hundreds. Russian and Turkish military specialists have died tragically," the statement added.
Kremlin spokesman Dmitry Peskov declined to comment to journalists, referring all questions to the foreign and defense ministries. Russian foreign ministry spokespeople declined immediate comment.
