Damascus vowed Wednesday to respond to a planned Turkish invasion of northeastern Syria, saying it condemned Ankara's "hostile intentions."

Damascus "is determined and willing to confront a Turkish assault using all legitimate means," said a foreign ministry statement carried by state news agency SANA, condemning Ankara's "hawkish statements, hostile intentions... and military build-up" along the border.

The ministry said the "hostile actions" of the Turkish government revealed its "expansionist ambitions," saying an attack on Syrian territory "could not be justified."

It said it held "some Kurdish groups (in Syria) responsible" for the current situation on the border, but would still be ready to "embrace" them if they decide to return to the fold.

In the early part of the eight-year-old civil war in Syria, Kurdish forces took control of Kurdish-majority areas of the north and east and set up their own autonomous institutions.

When the Islamic State group swept across the region in 2014, they mounted a fierce defence of their heartland and became the US-led coalition's main military partner on the ground.

Ankara strongly opposed Washington's support for Kurdish forces in Syria citing their links to the outlawed Kurdistan Workers' Party (PKK) which has fought a deadly insurgency against the Turkish state since 1984.

Damascus rejects Kurdish self-rule and wants central government institutions restored in Kurdish-held areas.

The Kurds want protection from the long-threatened Turkish offensive.

Weakened by Washington's decision to withdraw most of its troops following the capture of the last vestige of IS's "caliphate" in March, the Kurdish-led alliance has opened talks with Damascus.

But the negotiations have yet to bear fruit.

Turkey has already carried out two cross-border offensives into Syria, including one in 2018 that saw it and allied Syria rebels overrun the majority Kurdish Afrin enclave in the northwest.