BEIRUT: Dozens of relatives of fighters were killed on Fridayin new US-led strikes on Syria, just hours after the UN urged nations striking the jihadists to protect civilians.

Bombing raids by the US-led coalition have pounded positions of the militant Islamic State group across Iraq and Syria since the jihadist group claimed responsibility for the devastating bombing of a concert in Manchester on Monday.

Scores of civilians, many of them families of IS members, have been killed in bombing raids in recent days on the eastern Syrian town of Mayadeen, held by IS since 2014.

Early on Friday, at least 80 relatives of IS fighters were killed in US-led coalition bombardment, according to the Syrian Observatory for Human Rights.

`The toll includes 33 children.

They were f amilies seeking refuge inthe town`s municipal building,` said Observatory head Rami Abdel Rahman. `This is the highest toll for relatives of IS members in Syria,` he said.

Coalition strikes on the town killed 37 civilians on Thursday night after 15 had been killed on Wednesday, according to the Britainbased Observatory.

The US military on Friday confirmed that it had struck `near Mayadeen` on May 25 and 26, but said it was `still assessing the results of those strikes`, according to Pentagon spokesman Eric Pahon.

The US military insists that it takes every precaution to avoid hitting civilians, but the United Nations on Friday urged parties bombing IS to do more.

UNhumanrightschief ZeidRa`ad Al Hussein said `all states` whose air forces are active in the anti-ISmissions needed `to take much greater care to distinguish between legitimate military targets and civilians`.

The Observatory gathered its information from civilian and medical sources on the ground in IS-held Mayadeen.

The town has seen an influx of displaced families from IS-held territory in Iraq and Syria, including its bastion Raga.

It is in Syria`s oil-rich east near the border with Iraq a region considered a prize by many of IS`s enemies including the Syrian army.

Troops loyal to President Bashar al-Assad have been waging a multipronged offensive east to reach the strategic border territory.

They scored a key victory this week by linking the capital Damascus to the Unesco World Heritage city of Palmyra in centralSyria.

It was the first time the government was in full control of the Damascus-Palmyra highway since 2014, according to Abdel Rahman.

With backing from Russian air strikes, regime fighters `pushed IS fighters out of desert territory amounting to more than 1,000 square kilometres,` he said on Friday.

According to geography expert Fabrice Balanche, the government now controls 46 percent of Syria, compared with 36 percent in March.

Kurdish forces and IS each control 21 percent, and rebels just 12 per cent.

A decades-old ally of Damascus, Moscow has been carrying out air strikes in support of Assad`s troops since September 2015 a year af ter the American-led coalition began targeting IS in Syria.-AFP