BEIRUT • United States-backed militias in Syria said they came under attack last Saturday from Russian jets and Syrian government forces in Deir al-Zor province, a flashpoint in an increasingly complex battlefield, though Russia has denied the accusation.
The Syrian Democratic Forces (SDF), an alliance of Kurdish and Arab militias fighting with the US-led coalition, said six of its fighters were wounded in the strike.
The Pentagon said Russia bombed a position east of the Euphrates River, where it knew SDF fighters and coalition advisers were stationed. The jets did not injure coalition forces, it said.
Washington and Moscow support separate offensives in the Syrian conflict, with both advancing against Islamic State in Iraq and Syria (ISIS) militants in the eastern region that borders Iraq.
"Our forces east of the Euphrates were hit with an attack from the Russian aircraft and Syrian regime forces, targeting our units in the industrial zone," the SDF said in a statement.
The SDF accused Damascus of trying to obstruct its fighters.
Number of injured fighters from the Syrian Democratic Forces, an alliance of Kurdish and Arab militias fighting with the US-led coalition.
Such attacks "waste energies that should be used against terrorism... and open the door to side conflicts", it said.
Russia's Defence Ministry yesterday rejected the allegations, saying its planes targeted only ISIS militants and that it had warned the US well in advance of its operational plans.
Major-General Igor Konashenkov said Russian planes had carried out only carefully targeted strikes in the area based on information that had been confirmed from multiple sources.
Assaults by the Russian-backed Syrian army and the US-backed SDF have at times raised fears of clashes that could stoke tensions between the competing world powers.
Both offensives have converged on ISIS from opposite sides of the Euphrates River that bisects the oil-rich Deir al-Zor province, ISIS' last major foothold in Syria.
Syrian troops with Iran-backed militias have closed in from the west since last week, while the SDF advances from the east.
Russian and US battles against ISIS in Syria have mostly stayed out of each other's way, with the Euphrates often acting as a dividing line.
Talks have been under way to extend a formal demarcation line, officials have said.
The "caliphate" that ISIS said in 2014 it had established, spanning Iraq and Syria, effectively collapsed in July when an Iraqi offensive captured the city of Mosul.
In Syria, the militants have lost much of their headquarters in Raqqa to the SDF with the help of air strikes and special forces from the US-led coalition.
Yesterday, Syrian troops seized the al-Jafra suburb on the western bank of the Euphrates River, tightening the noose around ISIS, a Syrian military source said.
"They have no outlet except crossing the Euphrates towards the eastern bank and fleeing towards the desert, or (the towns of) al-Bukamal and al-Mayadin," the source told Reuters.
The US coalition has said the SDF does not plan to enter Deir al-Zor city.
Meanwhile, Russia's Foreign Ministry said yesterday that US Secretary of State Rex Tillerson had phoned Russian Foreign Minister Sergei Lavrov last Saturday to discuss the Syria situation and how the "anti-terrorism" battle on the ground was playing out.
However, the Russian Foreign Ministry did not say in its statement whether the two men had discussed the US' allegation of the attack by Russian jets.