DAMASCUS – More than 30 civilians and Kurdish-led fighters were killed on Tuesday in an Islamic State group attack near a refugee camp on the Syrian side of the border with Iraq.

The ISIS terrorists targeted a makeshift camp for displaced Syrians and Iraqi refugees at Rajm al-Salibi, near the town of Shaddadi in Hassakeh province.

The militants also clashed with members of the Syrian Democratic Forces (SDF) stationed at a nearby checkpoint, a UK-based monitoring group reports.

The attack came as the Kurdish-Arab alliance known as the Syrian Democratic Forces presses an offensive against IS in the town of Tabqa as part of an assault on the bastion Raqa.

“At least five suicide attackers blew themselves up outside and inside a camp for Iraqi refugees and displaced Syrians in Hasakeh province,” said Rami Abdel Rahman, the head of the Syrian Observatory for Human Rights monitoring group.

The US-backed alliance is spearheading the battle against IS in eastern Syria.

Its Kurdish and Arab fighters are close to taking control of the strategically important Euphrates River Valley town of Tabqa and will soon launch an offensive to retake the de facto IS capital of Raqqa.

The makeshift camp lies in the Rajm al-Salibeh area just inside Syrian territory, and at least 21 of the dead were displaced Syrians or Iraqi refugees, the Observatory said.

Civilians fleeing ISIS in both Syria and Iraq have made their way to the desolate border region seeking protection and onward passage to safety in Kurdish-controlled territory. But conditions in the area are harsh, with little shelter and authorities often overstretched.

ISIS once controlled large parts of Hasakeh province, but it has been pushed out of almost all of it, with Kurdish authorities now in control of most of the area.

Syria’s government maintains a small presence in the province, mostly in its capital Hasakeh city.

But the terrorist group remains a potent power in neighbouring Deir Ezzor province, from which many Syrians arriving at the border post are fleeing.

Backed by a US-led air coalition, the SDF has waged a months-long campaign against the militants across northern Syria and is now closing in on their bastion of Raqa.

In recent days, it has captured most of the key town of Tabqa, which occupies a strategic position on a supply route about 55 kilometres west of Raqa city.

More than 320,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests.

The war has drawn in foreign armies and fighters, including militants fighting alongside ISIS.

The group is also on the defensive in neighbouring Iraq, where the army and allied fighters are pushing to recapture the city of Mosul from ISIS.