The U.S. flag flutters on a military vehicle in Manbij countryside, Syria, on May 12, 2018. (Reuters file photo)

DAMASCUS, Dec. 10 (Xinhua) -- The U.S.-led coalition on Monday sent military gear to the frontline in eastern Syria amid continuing battles between the U.S.-backed Syrian Democratic Forces (SDF) and Islamic State (IS) militants, a war monitor reported.

A military convoy of seven Humvees and two other vehicles stacked with shells and missiles as well as a tank reached the frontline between the Kurdish-led SDF and the IS militants on the outskirts of the town of Hajin in eastern Deir al-Zour province, according to the Syrian Observatory for Human Rights.

The backup comes as battles are ongoing between the SDF and IS near Hajin, one of the areas in the last vestige of territory under the group's control on the eastern bank of Euphrates River in Deir al-Zour.

A day earlier, the watchdog group said the SDF brought 500 additional fighters to the frontline to take part in the battles to defeat IS in Hajin and the remaining IS-held areas in eastern Deir al-Zour.

Meanwhile, the observatory said the SDF secured the evacuation of 500 civilians, mostly women, children and elderly people, from Hajin to areas under the control of the Kurdish-led militia on Monday.

With the latest evacuation, the SDF has secured the departure of 1,100 civilians from Hajin since Nov. 30, said the observatory.

The latest military buildup around Hajin comes as SDF and allied Kurdish militias failed to hold on to the positions they had advanced to in the town.

The IS recently launched a counter-offensive and captured almost all of Hajin after the SDF had seized 70 percent of the town in recent days.

The SDF, with the backing of U.S.-led airstrikes, has launched a campaign to defeat the IS on the eastern bank of the Euphrates River since Sept. 10.

A total of 849 IS militants and 508 SDF fighters have been killed, according to a report released by the observatory on Saturday.