ISTANBUL -- Turkey's defence minister said Saturday that military officials with Turkey and the United States have begun work to create a "safe zone" along its border in northeastern Syria.

Turkey's official Anadolu news agency quoted Defence Minister Hulusi Akar as saying that generals from Turkey and the U.S. had begun work in a joint operations centre in the Turkish province of Sanliurfa to set up the zone and that joint helicopter patrols were set to begin.

Turkey has been pressing to control -- in co-ordination with the U.S. -- a 19-25 mile (30-40 kilometre) deep zone within civil war-ravaged Syria, running east of the Euphrates River all the way to the border with Iraq.

Turkey wants the region along its border to be clear of Syrian Kurdish forces and has threatened on numerous occasions to launch a new operation in Syria against Syrian Kurdish forces if such a zone is not established.

Turkey sees the Syrian Kurdish fighters, who make up the majority of the Syrian Democratic Forces and are allied with the U.S., as terrorists aligned with a Kurdish insurgency within Turkey. American troops are stationed in northeast Syria, along with the Kurdish forces, and have fought the Islamic State group together. The differing positions on the Kurdish fighters have become a major source of tension between NATO allies Turkey and the U.S.

Syria's government has called the agreement reached earlier this month for a safe zone a serious escalation that violates its sovereignty. It said it was part of Turkey's "expansionist ambitions" in Syria, aided by Washington and its Syrian allies, the Kurdish-led forces.

Akar on Saturday also criticized the Syrian government for violating a de-escalation agreement in northwestern Idlib province after it captured a string of villages.

He said Turkey would retaliate if observations posts manned by Turkish troops are attacked.