US anti-IS airstrikes 'kill scores of civilians in Syria'

At least 80 civilians were killed on Friday in US-led airstrikes on the town of Mayadeen, the Syrian Observatory for Human Rights reported.

Most of the deceased are understood to be relatives of Islamic State group militants.

The US-led coalition has stepped up its campaign against Islamic State group positions across Iraq and Syria since the group claimed responsibility for a suicide bombing in Manchester which killed 22 people.

"The toll includes 33 children. They were families seeking refuge in the town's municipal building," said Observatory head Rami Abdel Rahman. 

"This is the highest toll for relatives of IS members in Syria," he told AFP.

Airstrikes on Mayadeen also killed 37 civilians on Thursday night, while a further 15 were killed on Wednesday, the UK-based Observatory said.

The US military confirmed it had targeted an area near Mayadeen on May 25 and May 26, but said it was still "assessing the results of those strikes", Pentagon spokesman Eric Pahon said.

The toll includes 33 children. They were families seeking refuge in the town's municipal building

The Observatory gathers its information from a network of 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 Raqqa.

UN human rights chief Zeid Ra'ad Al Hussein said "all states" whose air forces are active in the anti-IS missions needed "to take much greater care to distinguish between legitimate military targets and civilians".

The 68-member coalition began bombing IS in Iraq in the summer of 2014, and expanded operations to Syria on September 23 that year.

The coalition is now supporting twin ground offensives against the Islamic State group's main cities, Raqqa in Syria and Mosul in Iraq.

Earlier on Thursday, the Pentagon concluded that at least 105 civilians had been killed in an airstrike targeting IS in Mosul in March.

Before the latest revelation, the US military had said coalition airstrikes in Iraq and Syria had "unintentionally" killed 352 civilians since 2014.

Rights groups put the number much higher, and the Observatory this week reported the highest monthly civilian death toll for the coalition's operations in Syria.

It said between April 23 and May 23, coalition strikes killed 225 civilians in Syria, including dozens of children.

Reports of civilian casualties in the air campaign have swelled in recent days. 

Syria has been embroiled in fighting since 2011 when anti-government protests were brutally put down by regime forces sparking a larger armed uprising.

The fighting has cost Syria nearly 500,000 lives, the vast majority victims of regime bombing.

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