ANKARA, Jan. 21 (Xinhua) -- Turkey has started a land operation against the Syrian Kurdish militants with land troops entering Syria's Afrin at 11:05 local time (0805 GMT) on Sunday, Prime Minister Binali Yildirim announced.

The military operation will aim to establish a 30 km security zone into the Afrin province from Turkish border, he told in a briefing to journalists.

Turkey launched the Operation Olive Branch on Saturday which aims to clear its borders from the People's Protection Units (YPG), a Kurdish group considered by Ankara as the Syrian affiliate of the Kurdistan Workers' Party (PKK).

"The operation will be carried out in four phases and will be done in a very rapid manner. Any support to terrorists in Afrin will be the target of this operation," Yildirim stressed.

There is nearly 8,000-10,000 "terrorist presence" in Afrin, he said.

Meanwhile, the prime minister noted that there was no opposition from the United States, and Iran did not oppose the operation but expressed some concerns.

He added that information about the operation was given to the Syrian government via Russia and Iran.

Turkey's Afrin incursion would not affect the processes of Sochi and Astana, he said.

Turkish Armed Forces and the Free Syrian Army rebels have advanced 5 km inside Afrin as part of Operation Olive Branch, state-run Anadolu Agency reported.

"Operation Olive Branch continues as planned and the ground offensive has begun," the military said in a statement on the second day of the military operation.