In August, Turkey began an ambitious military operation to back moderate Syrian opposition fighters to remove jihadists from its border and stop the westward advance of Syrian Kurdish forces that Ankara considers "terrorists".

"We are determined to clear the PYD terror organisation from Manbij as soon as possible," Erdogan said, referring to the Kurdish Democratic Union.

"They will have to get out, leave and go beyond the Euphrates. If they do not go, we will do what is required," he told a group of neighbourhood chiefs in Ankara.

The Kurdish YPG militia wrested control of Manbij from IS in August as part of a Kurdish-led alliance with Arab fighters called the Syrian Democratic Forces.

Ankara views the PYD and the YPG (People's Protection Units) as terror groups linked to Turkey's outlawed Kurdistan Workers' Party (PKK).

The PKK -- proscribed as a terrorist organisation by Turkey and its Western allies -- has been waging an insurgency in Turkey since 1984.

Erdogan has persistently called on the YPG to withdraw east of the Euphrates River.

Turkey wants to stop the creation of an autonomous Kurdish "canton" in northern Syria. Ankara fears such a zone would embolden Kurdish separatists in Turkey.

Erdogan said the goal of the Turkey-backed rebels was to recapture Al-Bab city in northern Syria from the Islamic State group (IS) then go forward to Manbij.

Experts say rebels supported by Ankara are a varied collection of different Syrian opposition brigades rather than a single organised force.

Since Wednesday last week, Turkey has renewed its strikes on Kurdish forces, hitting dozens of YPG targets in Syria.

Ankara claimed on Thursday it had killed up to 200 Syrian Kurdish fighters but the Syrian Observatory for Human Rights said at least 11 rebels were killed.

Ankara has provided air support as well as tanks to Syrian opposition rebels in its operation dubbed "Euphrates Shield".

So far, the Turkish army says 1,265 square kilometres (488 square miles) of territory has been captured including the emblematic IS stronghold of Dabiq. The army also says the Turkish border has been cleared of IS elements.