Turkish President Erdogan challenges US support for Kurdish fighters in operation to seize Raqqa from ISIL.

Turkey’s president said on Monday it is “naive” to use Syrian Kurdish fighters – whom he branded terrorists – to retake the Islamic State of Iraq and the Levant (ISIL) group’s stronghold of Raqqa.

Fighters aligned with the US-backed, Kurdish-led Syrian Democratic Forces (SDF) are currently pushing ahead in an offensive towards ISIL’s so-called capital in northern Syria.

“No one in the world will buy this naive attitude of [attacking] Daesh with another terror organisation,” Turkish President Recep Tayyip Erdogan said on Monday, using an Arabic acronym for ISIL.

READ MORE: Syrian rebels announce offensive to retake Raqqa

Erdogan called the Syrian Kurdish groups fighting against ISIL “a side branch” of Turkey’s outlawed Kurdistan Workers’ Party (PKK), and criticised the United States, a NATO ally, for supporting such groups.

PKK, an armed group that has waged a three-decade insurgency against the Turkish state, is categorised as a “terrorist organisation” by the US, the European Union and Turkey.

‘Raqqa an Arab city’

“The use of non-Arab forces to liberate Raqqa will not contribute to peace,” Turkey’s Deputy Prime Minister Numan Kurtulmus also said on Monday.

Turkey would not like to see “Raqqa, which is an Arab city in its entirety, to be captured by elements that are not Arabs and to be administered by them,” Kurtulmus said after a cabinet meeting in Ankara.

“Legitimacy cannot be provided with the participation of armed terror organisations. It requires the participation of legitimate states and their armed forces,” he added.

Al Jazeera’s Mohammed Adow, reporting from Gaziantep on Turkey’s border with Syria, said that although the SDF called on international forces to assist the offensive, it has made it clear it does not want Turkish military involvement.

The Turkish officials’ latest comments came a day after their top military leaders met NATO allies in Ankara to discuss Turkey’s grievances about the operation to take Raqqa.

“The coalition and Turkey will work together on the long-term plan for seizing, holding, and governing Raqqa,” General Joe Dunford, chairman of the US Joint Chiefs of Staff, said following a four-and-a-half hour meeting with his Turkish counterpart, General Hulusi Akar.

READ MORE: Kurds deny forcing Arabs from Iraq’s Kirkuk

As the operation to retake Raqqa continues, the US will work with the Turks and others to determine the make-up of forces that move on Raqqa and govern it, he said in a statement on the Pentagon’s website on Monday.

“We always knew the SDF wasn’t the solution for holding and governing Raqqa,” Dunford said. “What we are working on right now is to find the right mix of forces for the operation.”

Turkey launched an operation inside Syria in August alongside allied rebel forces who have managed to capture Jarabulus and the symbolically important town of Dabiq from ISIL.

But one of the operation’s goals is also to check the advance of Syria’s Kurds. Turkish forces have carried out air strikes against Kurdish positions in northern Syria.