US-backed Syria militia 'hit by Russian bombing'

US-backed Syrian Democratic Forces have been hit by Russian bombing and mortar fire at a recently captured gas plant in eastern Syria, the mostly Kurdish militia said on Monday.

It comes days after the Kurdish-led force captured the Conoco gas plant from the Islamic State group.

The Syrian Democratic Forces entry into Deir az-Zour where a Russian-backed, Syrian regime offensive is taking place.

The race to carve up territory has led to tensions between the two sides with Kurdish militias previously targeted by pro-Damascus forces. 

"Russian air strikes and mortar fire hit the Conoco gas plant where a large number of our forces are stationed, and the preliminary toll is at least six wounded," SDF spokeswoman Lilwa Abdallah told AFP.

US special forces are also thought to operate in the area.

Syrian regime forces followed up the alleged Russian bombing with an artillery bombardment of the SDF positions.

"We reserve the right to respond," added Abdallah.

The SDF is made up an alliance of Kurdish and Arab fighters and captured the Conoco plant from IS on Saturday.

The militia is based on the eastern side of the Euphrates River, which cuts through resource-rich Deir az-Zour province.

"De-conflict" zones in the area are supposed to prevent the two forces from clashing, but on 16 September six SDF fighters were wounded in air strikes by regime and Russian warplanes in the al-Sinaaiya area. Russia denies the claim.

Syria's eastern territories has become a potential battleground between the two sides, and the resource rich areas could be particularly lucrative prizes.

Professor Joshua Landis, of the University of Oklahoma, said both groups were heading for oil-rich territories. "Both the Syrian army and the SDF are making a play for the Euphrates Valley, where a great deal of Syria's oil is situated," he told The New Arab.

"Most wells are just north of the Euphrates. It now seems that the SDF, with US backing, wants that oil."Control over this oil gives the SDF a source of revenue for its semi-autonomous - and unrecognised - federal democratic polity in the Syrian Kurdish territories, and other territories they've captured from IS where they have established military councils, such as Manbij."

Agencies contributed to this story.