BEIRUT (Reuters) - Syrian state media reported that the U.S.-led coalition fighting Islamic State struck Syrian army positions in eastern Syria early on Thursday, but the U.S. military denied knowledge of it.

Islamic State lost most of its territory in Syria last year, but retained some remote desert areas and has attacked the army and allied forces in recent weeks. The coalition also recently restarted its own campaign against the jihadist group in Syria.

“Some of our military sites between Albu Kamal and Humeima were exposed at dawn today to aggression launched by U.S. coalition jets,” state news agency SANA reported, citing a military source.

The strikes caused only material damage and came within 24 hours of an Islamic State attack on Syrian army positions in the same region, SANA reported.

A military media unit run by Lebanon’s Hezbollah, an ally of Damascus, said the strikes were near T2, an energy installation near the border with Iraq about 100 km (60 miles) west of the Euphrates.

A U.S. military official denied any knowledge of the strikes. “We have no operational reporting of a U.S.-led coalition strike against pro-Syrian regime targets or forces,” Captain Bill Urban, a spokesman for U.S. Central Command, told Reuters.

Another Pentagon spokesman, who spoke on condition of anonymity, said: “We have no information to substantiate those reports.”

Eastern Syria was mostly held by Islamic State until last year, when two rival military campaigns swept it from most of its territory, leaving only remnants in remote pockets of the desert.

The campaign by the Syrian army, backed by Russia, Iran and Shi’ite militias including Hezbollah, operated mostly on the west side of the Euphrates river.

A rival campaign by the Syrian Democratic Forces (SDF)alliance of Kurdish and Arab militias, backed by the U.S.-led coalition, mostly took territory on the east side of the river.

A war monitor, the Britain-based Syrian Observatory for Human Rights, reported on Thursday that Islamic State militants had been fighting pro-Syrian government forces to the west of the Euphrates, and the SDF to its east, on Wednesday night.

It reported that Thursday’s strikes had killed some members of a foreign militia supporting the Syrian government.

Communication between Russia and the United States averted most clashes between them. However, the coalition has struck pro-Syrian government forces that it said were attempting to attack coalition positions.

The U.S. military operating outside the coalition also maintains a base at Tanf in the eastern Syrian desert near the borders with Iraq and Jordan and last year struck pro-government forces moving along a road toward it.