US soldiers aboard Humvee armoured vehicles have been watching from a distance as two of their allies, Turkish-backed forces and a Kurd-Arab alliance, battle it out for control of Manbij in northern Syria.

An AFP correspondent on Friday saw the American soldiers on patrol north of the city of Manbij, just miles from the fierce clashes taking place further west.

Turkish forces and allied Syrian rebels have tried since Wednesday to capture Manbij, a former bastion of the Islamic State group, now under the control of the US-backed Syrian Democratic Forces (SDF) alliance.

The SDF is dominated by fighters known as the Turkish People's Protection Units (YPG) which Ankara brands as "terrorists".

Turkey launched a military campaign inside Syria in August, backing opposition rebels who captured a number of towns from IS jihadists, including Al-Bab near the Turkish border.

President Recep Tayyip Erdogan this week said the next target would be Manbij, in Aleppo province.

And on Thursday, Turkish Foreign Minister Mevlut Cavusoglu threatened to strike the YPG unless they pull out of the northern city.

On Friday, fighters from the SDF were on high alert in a farm near Arima, a village located half-way between Al-Bab and Manbij.

Heavy fighting and bombardment could be heard in the distance.

Serhaldan, a Kurdish commander who only gave his first name, told AFP that fighters from the Turkish-backed "Euphrates Shield" campaign "have attacked our forces but we repelled them".

He said the Turkish forces and their allies were using mortar rounds and heavy weapons as well as multiple rocket launchers.

The US-led "coalition is not helping us", he said, pointing  towards the area of combat.

- 'High level coordination' -

Coalition aircraft have in the past carried out air strikes against IS and other jihadists in Syria, and provided cover for SDF forces in the past.

But on Friday, the AFP correspondent said no aircraft could be seen over the area.

According to a senior source in the SDF, "Votel confirmed the coalition's commitment to protecting Manbij from any attacks waged by Turkey or supported by it, as part of its previous commitment to protecting the area."Last week, General Joseph Votel, who heads US Central Command (Centcom), made a secret visit to northern Syria where he met with SDF leaders.

But Votel's spokesman, Colonel John Thomas, said that, while the general supported a peaceful transition of Manbij to a "thriving city", he did not say if the US would stop any Turkish move towards it.

The United States has special operations forces advising the SDF on the ground in Syria, but no combat units.

Sherfan Darwish, spokesman of the Manbij Military Council which is part of the SDF, tried to play down the absence of US forces in Manbij.

"The coalition is on patrol along the Sarjur river (north of Manbij) and there is coordination with the coalition at the highest level," Darwish told AFP.

"All our fighters in Manbij were trained by the Americans," he added. 

source: AFP