MOSCOW, Sept. 7 (Xinhua) — Russia on Wednesday expressed serious concern about the advance of Turkish troops and Ankara-backed opposition militias inside Syria.

"We draw attention to the fact that these actions are carried out without the consent of the legitimate Syrian authorities and without the approval of the UN Security Council, thus raising questions about the sovereignty and territorial integrity of Syria," the Russian Foreign Ministry said in a statement.

Turkish actions could further complicate the situation in Syria, the ministry said, adding that it would have a negative impact on international efforts to develop a peaceful settlement platform, as well as the ongoing humanitarian aid in the war-raged country.

The ministry called Ankara to refrain from any steps that might lead to increased destabilization of the situation in Syria.

Turkish military on Aug. 24 started a cross-border operation against the Islamic State terrorist group and Kurdish groups related to the Kurdistan Workers Party, which Ankara labels as a terror organization.