UNITED NATIONS, Aug. 19 (Xinhua) -- Reports of an air attack on a Turkish military convoy in northwest Syria, which claimed three civilian lives on Monday, are of "grave concern" to the United Nations and "a significant risk to regional security," a UN spokesman said.

Stephane Dujarric, spokesman for UN Secretary-General Antonio Guterres, told reporters at a regular briefing, "Turkey's defense ministry has indicated (that) this has resulted in multiple casualties."

Xinhua reported from Ankara that the ministry said three civilians were killed and 12 others injured.

"These reports are of grave concern to us and reminds us that violence in Idlib is not just a humanitarian issue, it also poses a significant risk to regional security," Dujarric said.

The United Nations reiterated the call for an urgent de-escalation of the situation in the northwestern part of Syria and for all parties to recommit fully to the cease-fire arrangement agreed by Russia and Turkey in 2018, he said.