Kurdish fighters warn of 'all-out war' in response to Turkey threats

US-backed fighters have warned they would "not hesitate to turn any unprovoked [Turkish] attack into an all-out war" if Ankara pushes ahead with its threats of an offensive in Syria.

Territory in eastern Syria controlled by the mostly Kurdish Syrian Democratic Forces (SDF) has been the focus of Turkish threats of an imminent military operation. 

An air and ground operation east of the Euphrates river in Syria could start at any time, President Recep Tayyip Erdogan said on Saturday. 

Erdogan has accused the US of not doing enough to expel Kurdish forces from areas near the Turkish border, despite setting up a jointly patrolled buffer zone last month. 

Erdogan said Turkey aimed to "water the east of Euphrates with fountains of peace" and settle refugees there.

"We gave all warnings to our interlocutors regarding the east of Euphrates, and we have acted with sufficient patience," he said at the opening of his AK Party's annual camp.

"We've made our preparations, we've completed our operation plans, given the necessary instructions." He added that air and ground actions could start "as soon as today or tomorrow".

Turkey considers the SDF's leading force, the YPG militia, a terrorist organisation linked to the separatist Kurdistan Workers' Party (PKK) based in Turkey. 

Turkey has accused the United States, which helped the YPG defeat Islamic State militants in Syria, of moving too slowly to create the zone. They are at odds over how far it should extend into Syria and who should control it.

Ankara wants the zone to stretch 30 km inside Syria and to be cleared of YPG fighters. It has repeatedly warned of launching an offensive on its own into northeast Syria, where US forces are stationed alongside the SDF.

The SDF, which has said it will pull back up to 14 km on some parts of the border, is committed to the agreements under US-Turkish talks and will remain so if "dangerous threats" stop, its spokesman, Mustafa Bali, said.

Kurdish commanders have warned that a Turkish border attack would lead to a resurgence of Islamic State militants, from which the SDF seized vast territory in north and east Syria.

"Simply, there will be a big gap in the towns that our forces will withdraw from to go to defend the border, and this will give Daesh [IS] the opportunity to return," Bali said.