ANKARA, Jan. 20 (Xinhua) -- Turkish Foreign Ministry informed ambassadors of Iran, Russia and the U.S. in Ankara about a military operation launched by Turkey's army in Syria's Afrin on Saturday, a ministry official told Xinhua on condition of anonymity.

Turkish Foreign Minister Mevlut Cavusoglu also held a phone conversation with U.S. counterpart Rex Tillerson in the wake of the announcement of the air strikes by Turkish Air forces, at Washington's request, the official also said.

Turkish President Recep Tayyip Erdogan announced on Saturday the military operation in Syria's Afrin has "actively" started.

Turkey is determined to ensure its national security and to clear its borders of the People's Protection Units (YPG), which is considered by Ankara as the Syrian affiliate of the Kurdistan Workers' Party (PKK).

Turkish war jets have been hitting the YPG positions in Afrin on Saturday after days of shelling from the border.

The Turkish Army stated that the operation is named "Olive Branch" and started at 17.00 in local time.