ANKARA,— Turkish President Recep Tayyip Erdogan on Wednesday said Syrian Kurdish militia forces must remain outside the scope of a ceasefire agreed between Syria’s warring parties, in a blow to the deal days before it is due to be enforced.

Lashing out at Western policy in Syria, he said the Syrian Kurdish Democratic Union Party (PYD) and its People’s Protection Units (YPG) militia were a “terror group” just like Islamic State (IS) jihadists and the Al-Qaeda affiliated Al-Nusra Front.

The issue has already provoked a rare rift between Ankara and its chief NATO ally Washington, which works closely with the YPG as an effective fighting force against IS in Syria.

“If Daesh (IS) and Al-Nusra are kept outside the ceasefire, then the PYD-YPG must similarly be excluded from the ceasefire for it is a terrorist group just as they are,” Erdogan told local officials in Ankara.

The ceasefire deal was announced on Monday by Moscow and Washington but does not apply to the Islamic State group or Al-Nusra Front, an Al-Qaeda affiliate, and is due to take effect at midnight on Friday Damascus time.

The powerful Kurdish YPG forces which the U.S. and Russia consider an ally in the fight against IS, is the most effective group fighting IS in Syria, as the Kurdish militia has seized swathes of Syria from IS.

Turkey which still denies the constitutional existence of its own Kurds fears the creation of an autonomous Kurdish region in Syrian Kurdistan — similar to the Kurdistan region in northern Iraq — would spur the separatist ambitions of Turkey’s own Kurds numbering to 22.5 million of the country’s 78-million population.

Turkish Deputy Prime Minister Numan Kurtulmus said on Tuesday that Turkey is not optimistic over the implementation of a Syria ceasefire announced by the United States and Russia, threatening to keep up retaliatory artillery strikes against Kurdish fighters in Syrian Kurdistan.

Erdogan said Turkey welcomed the Syria ceasefire as “positive in principle” and said: “We support a ceasefire that will help our Syrian brothers breathe.”

But he warned that Turkey would be “on alert” against any steps that threaten its national security and would continue to closely monitor the ceasefire process.

The president said its key ally Washington’s approach towards the PYD did not bode well with the “alliance spirit”

“This is a matter of survival for Turkey,” Erdogan said. “Believe me, I barely understand how clearly we can explain for our allies to understand that they are at a crossroads on this issue.”

He quipped that if fighting IS was the only criteria, then the West should cooperate the Al-Nusra front which often battles the even more extremist IS jihadists.

Erdogan said the PYD and the YPG must be designated as “a terrorist organisation” by Turkey’s allies

“To accept it as a terrorist organisation, will it require that the PKK and PYD explode their bombs not in Ankara but in other (foreign) capitals?” he said.

Ankara blames the YPG for last week’s suicide car bomb attack in the Turkish capital that killed 29 people and fears the creation of a Kurdish stronghold along its southern border.

The YPG and PYD deny any involvement in the attack.

Turkey-based Kurdistan Freedom Falcons (TAK) group claimed the suicide car bombing of a convoy of military buses in Ankara but Turkish officials said the bomber was a Syrian Kurdish national working on behalf of the PYD.

Turkey defied international calls and keeps shelling Syrian Kurdistan (northern Syria) for the past week, insisting it would not allow Kurdish-led forces to seize key areas along the border.

Turkey also strongly opposed the PYD of Syrian Kurdistan taking part in UN-backed talks.

Moscow hopes that the next intra-Syrian reconciliation talks will be held on February 25 in Geneva and will include participation from the Kurds of Syrian Kurdistan, a source in the Russian Foreign Ministry said Saturday.

Syrian Kurds were not invited to Geneva peace talks last month despite the fact that Kurds make up some ten percent of the Syrian population and have been effective at fighting the Islamic State.