Russia's foreign ministry expressed deep concern on Wednesday at Turkey's military operation in Syria, warning of rising tension over Ankara's targeting of Kurdish militia fighters at the border.
"We are deeply concerned at what is happening in the Syrian-Turkish border area," the ministry said in a statement.
Turkey's air and ground operation risks "further degeneration of the situation in the conflict zone," Moscow warned.
The Turkish offensive targeting both Islamic State extremists and Syrian Kurdish militias could lead to deaths among peaceful civilians and "flare-ups of inter-ethnic tensions between Kurds and Arabs," it added.
Russia, a major ally of the Syrian regime, has strengthened its relationship with Syria's Kurds and a Kurdish representative office recently opened in Moscow.