Turkey will never allow the formation of an "artificial state" in northern Syria, Prime Minister Binali Yildirim said on Sunday, referring to the U.S.-backed Kurdish fighters whose advance Ankara is now aiming to stop.

Turkey and its allies opened a new line of attack in northern Syria on Saturday, as Turkish tanks rolled across the border and Syrian fighters swept in from the west to take villages held by Islamic State and check the advance of the US-backed Syrian Kurdish YPG.
Turkey launched its operation in Syria, called Euphrates Shield, on Aug.24, driving out Islamic State from the border town of Jarablus. Much of the focus since has been on the YPG militia, as Ankara fears its growing control of northern Syria.
"We will never allow the formation of an artificial state in the north of Syria," Yildirim said in a speech in the southeastern city of Diyarbakir, where he announced an investment programme to rebuild parts of the largely Kurdish region that have been destroyed by security operations.
"We are there with Euphrates Shield, we are there to protect our border, to provide for our citizens safety of life and property, and to ensure Syria's integrity."
Turkey is fighting a three-decade-old Kurdish insurgency in the southeast and fears that the YPG's advances will embolden militants at home. Turkey considers the YPG a terrorist organisation and an extension of the outlawed Kurdistan Workers Party (PKK).
While the United States and Europe also regard the PKK as a terrorist group, Washington sees the YPG as a separate entity and as its most effective partner in the fight against Islamic State in Syria. That position has caused friction with Turkey, a NATO member and a partner in the fight against Islamic State.

Kurdish backlash

Some Kurds have criticised Turkey for its role in Syria. A demonstration broke out along the Syrian border on Friday, where Turkey is building a concrete wall. Police used tear gas and water cannon to drive the protesters back.
At a rally in Istanbul on Sunday, the co-head of Turkey's Kurdish-rooted Peoples' Democratic Party (HDP) denounced the incursion into Syria as an "invasion".
"The government, which says it wants to stop ISIS (Islamic State) with the Jarablus invasion, has no credibility. The invasion of Jarablus is totally an adversarial approach against Kurds and we will never accept it," Selahattin Demirtas told reporters.
President Tayyip Erdogan on Sunday raised concern about the formation of a "terror corridor" along Turkey's Syrian border.
Speaking to reporters after a meeting with U.S. President Barack Obama at the G20 gathering of world leaders in China, Erdogan said: It is our wish that a terror corridor not be formed across our southern border".
Erdogan has repeatedly said that Turkey's allies should not be making a distinction between Islamic State and the YPG as both groups pose a threat to Turkey.
Separately, state-run Anadolu Agency said Turkish jets hit four Islamic State positions late on Saturday evening in Syria's northwestern Aleppo province as part of the operation, citing security sources.
The warplanes hit three targets in the al-Kaldi area and another in the Wuguf region, Anadolu said, citing the sources.