BEIRUT (AP) — A Syrian Kurdish militia that Turkey views as a terrorist group says Russian servicemen are training its forces in northern Syria.

Redur Khalil, a spokesman for the People's Protection Units, or YPG, said the Russian forces were there "by agreement," in comments carried Monday by the group's Hawar News agency.

The U.S.-backed YPG has proven to be one of the most effective forces battling the Islamic State group, and has carved out a semi-autonomous zone along the Turkish frontier.

It maintains neutral relations with the Russian-backed Syrian government and sometimes clashes with Turkish-backed Syrian opposition forces.

Turkey views the YPG as an extension of the Kurdish insurgency in its southeast.

Khalil says the training mission is a step toward "direct contacts" with Russia.

Russia's Defense Ministry had no immediate comment.