Up to 100,000 civilians trapped in Syria's Raqa, UN declares

As many as 100,000 civilians are trapped in Syria's Raqa, as US-backed fighters battle to retake the city from the Islamic State group, the UN rights chief warned Wednesday.

UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein voiced grave concern for the fate of civilians caught up in the anti-IS offensive in Raqa.

According to data collected by his office, at least 173 civilians have been killed by air and ground strikes in the city since June 1, but it acknowledged that that estimate was likely conservative, and the real death toll could be much higher.

At the same time, "up to 100,000 civilians are effectively trapped as the air and ground offensive intensifies," it said in a statement, adding that IS fighters were reportedly preventing people from fleeing.

Civilians who try to leave also risk being killed by landmines or getting caught in the crossfire, it said.

"The intense bombardment of Al-Raqa over the past three weeks has reportedly left civilians terrified and confused about where they can seek refuge as they are caught between ISIL's monstrosities and the fierce battle to defeat it," Zeid said in the statement, using another acronym for IS.

"The large number of civilian casualties indicates that much more needs to be done by the parties to ensure protection of the civilian population," he said.

The alliance, known as the Syrian Democratic Forces (SDF), broke into Raqa on June 6 after a months-long operation to surround it and have since seized about a quarter of the city.

Before the offensive began, an estimated 300,000 civilians once lived under IS rule in Raqa, including 80,000 displaced from other parts of Syria before the group seized the city.

IS overran Raqa in 2014, transforming it into the de facto Syrian capital of its self-declared "caliphate".

It became infamous as the scene of some of the group's worst atrocities, including public beheadings, and is thought to have been a hub for planning attacks overseas.

Zeid on Wednesday called on all forces battling IS in Raqa, including international forces, to review their operations and ensure they were in "full compliance with international law, including taking all feasible precautions to avoid loss of civilian lives".

"Civilians must not be sacrificed for the sake of rapid military victories," he insisted, calling on all sides to help ensure that civilians who want to leave the city can do so safely.

Zeid also voiced alarm at reports of violation by SDF forces in areas under their control, including "looting, abductions, arbitrary detentions during screening processes as well as the recruitment of children".