Two Turkish and two US helicopters held a joint flight on Thursday over the planned safe zone in northern Syria, said Turkish Defense Ministry.

"A joint flight was made with two Turkish and two US helicopters within the scope of Safe Zone First Phase Applications in east of Euphrates in Syria," said the ministry in a statement on social media.

The two countries carried out the first reconnaissance flight on Aug. 24, said Turkish Defense Minister Hulusi Akar earlier.

On Aug. 7, Turkish and US officials agreed to set up a safe zone and develop a "peace corridor" in northern Syria which would address Ankara's security concerns about a Kurdish faction that controls the territory.

The safe zone would also facilitate the return of displaced Syrians currently living in Turkey to their home country.

Turkish drones started operating in northern Syria on Wednesday as part of the agreement.

Earlier in August, Turkish presidential spokesperson Ibrahim Kalin said joint patrols of the US and Turkish troops will begin soon in east of the Euphrates river.

The military officials from the two NATO allies have also established a joint operation center in Akcakale.

Washington and Ankara had been at odds for a long time over plans for northeastern Syria, where the United States has allied with the YPG, the Syrian offshoot of the Kurdistan Workers' Party that outlawed by Turkey, in battles against the Islamic State (IS) militants.