WASHINGTON — Officials at the United Nations have called for a halt to the U.S.-led air campaign against ISIS in Raqqa on humanitarian grounds.

“Now is the time to think of possibilities, pauses or otherwise that might facilitate the escape of civilians, knowing that Islamic State fighters are doing their absolute best to use them as human shields,” Jan Egeland, a special adviser to the UN Special Envoy for Syria, told reporters at a briefing in Geneva.

According to Egeland, there are five neighborhoods in Raqqa under ISIS control where nearly 20,000 civilians are concentrated, and constant air raids and shelling by the coalition are causing heavy civilian casualties.

“I cannot think of a worse place on earth now than in these five neighborhoods and for these 20,000 people,” he said.

The UN has called for similar humanitarian pauses in places such as Aleppo, Egeland said. However, the situation in Raqqa is worse because there is no communication with ISIS fighters in Raqqa who may be intentionally holding civilians as human shields, he explained.

“This is the time to try anything to allow their safe escape,” he added. “At the moment, few people leave because they are afraid for their lives, really. They fear certainly from those holding those areas, but they also fear for shelling and air raids.”

U.S.- backed Kurdish fighters known as the Syrian Democratic Forces are currently in their third month of fighting to liberate the de facto ISIS capital of Raqqa.

The SDF currently control nearly 60 percent of the embattled city, according to Maj. Gen. Rupert Jones, the deputy commanding general for Operation Inherent Resolve.

However, incremental gains by the SDF in the city have not come without a cost. According to recent reporting from the Syrian Observatory for Human Rights — a human rights watchdog group monitoring Syria — nearly 167 civilians were killed in coalition bombing early this week.

“We go to the very greatest lengths possible to protect civilians. We regret every single civilian casualty, and we would never destroy property unless we had to,” Jones said in a televised Pentagon briefing on Wednesday.

“If you want to liberate your towns and cities, it comes at a price. Our job is to ensure that price is as small as possible,” he added.

However, according to Donatella Rovera — Amnesty International’s senior crisis response adviser — the coalition’s air and artillery support to the SDF may not be in compliance with international law. 

Amnesty International has ”concerns” about the coalition’s conduct, she told Military Times. 

According to Rovera, Lt. Gen. Stephen Townsend’s claim earlier this summer that the coalition bombs every boat it sees in the Euphrates river is an example of the violation of the law of war. Townsend is the commander of Operation Inherent Resolve.

The Euphrates river is one of the main avenues of escape for civilians fleeing from ISIS, Rovera said. Bombing every boat would constitute an act of indiscriminate attack. 

Rovera praised efforts to seek a humanitarian pause in the coalition air campaign but warned that the fighting will simply resume soon after.

A ”change in modus operandi” is needed for the coalition’s air and artillery support to the SDF if the coalition wants to save civilian lives, she said.