The Syrian government has said that a US-Turkish agreement on establishing a so-called "safe zone" in north-east Syria is a "blatant violation" of its sovereignty, blaming the country's Kurds for the proposal.
"Syria categorically and blatantly rejects the agreement between the American and Turkish occupiers on the establishment of a so-called safe zone" in northern Syria, a foreign ministry source told state news agency SANA.
"Syria's Kurds who have accepted to become a tool in this aggressive US-Turkish project bear a historical responsibility" the source added, urging Kurdish groups to return to the fold.
Syria's Foreign Ministry released a statement on Thursday saying the agreement exposes Turkey's "expansionist ambitions."
It comes a day after Washington and Ankara announced they had agreed to form a coordination centre to set up the safe zone. No details were provided on the size or nature of the safe zone, but the deal appeared to provide some breathing room after Turkey had threatened an imminent attack on the Kurdish People's Protection Units (YPG), which control a large swathe of northern Syria.
The move may have averted a Turkish incursion into that part of Syria. Ankara seeks to push out US-allied Syrian Kurdish fighters from there as it considers them fighters terrorists, allied with a Kurdish insurgency inside Turkey.
Damascus said Syrian Kurdish groups "bear historic responsibility" for the US-Turkey deal and urged them to switch sides, aligning with the Syrian government instead.
Damascus has had no presence along the Turkish border since 2012.
A senior Syrian Kurdish official gave the deal a guarded welcome.
"This deal may mark the start of a new approach but we still need more details," Aldar Khalil said on Thursday.
"We will evaluate the agreement based on details and facts, not headlines."
The YPG has been a key US ally in the fight against ISIS.
But Ankara views it as a "terrorist" offshoot of the Kurdistan Workers Party (PKK), which has fought a bloody insurgency inside Turkey for the past 35 years.
As the fight against ISIS winds down in northeastern Syria, the prospect of a US military withdrawal has stoked Kurdish fears of a long threatened Turkish attack.
In recent weeks, Turkish media have repeatedly shown images of military convoys heading for the border area, carrying equipment and fighting units.