A Syrian man carries wood to be used for heating in the rebel-held town of Douma, on the eastern outskirts of Damascus, on January 3, 2017. (AFP/Xinhua)

DAMASCUS, Jan. 9 (Xinhua) -- Warplanes, believed to be with the U.S.-led anti-terror coalition, carried out airstrikes in Syria's eastern province of Deir al-Zour, killing at least 25 Islamic State (IS) group militants, a monitor group reported on Monday.

The airstrike was carried out on Sunday in the Kubar area in the western countryside of Deir al-Zour, beside the town of Ma'adan in al-Raqqa province's eastern countryside, IS's de facto capital, said the Syrian Observatory for Human Rights.

It added that four choppers, escorted by two warplanes securing the landing perimeter and scanning the area, landed in the towns of Kubar and Jazra in western Deir al-Zour.

A vehicle transporting IS members was struck in the operation, which killed all vehicle passengers, said the Observatory.

It added that airdropped members from the choppers set up checkpoints on the road between Kubar and a nearby water station, and between the water station and Jazra.

Citing what it called sources, the Observatory said airdropped members spoke Arabic, and did not harass civilians in the area during the operation.

The soldiers also attacked the water station near Kubar and fought IS militants, killing 25 militants and rounding up others, the Observatory said, adding that bodies of slain IS militants were taken by the airdropped soldiers.

It noted that the warplanes flew into the area from northern Syria.

The Syrian government has yet to comment on the operation.

Much of Deir al-Zour countryside is under IS control, while the city itself remains under government control, yet is heavily besieged by the terrorist group.