The US-led coalition in Syria says two of its troops were lightly injured when artillery rounds hit a base housing American troops in the country’s north-east.

The International Coalition for Operation Inherent Resolve said the two wounded coalition members were treated and returned to duty following the early Thursday attack at Green Village in Deir al-Zor province bordering Iraq.

Iraqi sources, speaking on the condition of anonymity, said those wounded were Americans, and that one of them suffered traumatic brain injury.

Green Village, located just east of the Euphrates River, is used by some of the several hundred US forces in Syria.

Iran-backed militias in Syria and Iraq have often targeted US bases in the two countries, vowing to drive out the Americans from the region.

A war monitor, the Britain-based Syrian Observatory for Human Rights, said five rockets were fired early Thursday from positions west of the river where Iran-backed fighters are concentrated.

On Wednesday night, three Katyusha rockets landed near an oil refinery in Iraq's northern semi-autonomous Kurdish region but no casualties or material damage were reported.

The Kawergosk refinery, about 20 kilometres north-west of the regional capital, Erbil, is one of the largest in the oil-rich area.

Nobody has immediately claimed responsibility for the attacks, which followed a series of assaults on US forces and their local partners in Iraq and Syria carried out by Iran and its allied paramilitary groups.