BEIRUT: The head of Syria’s main opposition-in-exile group called Thursday on world leaders to take “immediate action” to end government attacks on rebel-held suburbs of Damascus, amid reports that some 150 people have been killed in government airstrikes in the past 10 days.

Khaled Khoja, leader of the National Coalition, made the appeal at a news conference held from the group’s base in Turkey.

The government has been pounding the eastern Ghouta suburbs of Damascus for days as part of a military campaign against rebel-held districts east and south of the capital Damascus. Douma, a sprawling town east of Damascus, has taken the brunt of the airstrikes.

“The Assad regime’s killing of children and the elderly with rockets, barrel bombs, and toxic gases is as a crime as horrible as ISIS’ laughtering and burning of people alive,” Khoja said.

He said Assad’s “barbaric assault” on Douma constitutes a war crime and urged the U.N. to force the Syrian leader to stop indiscriminate bombardment of rebel-held territory.

Government batteries have rained shells and rockets on Douma and other rebel-held districts outside the city in attacks that activists say have been some of the worst they’ve seen, including dozens of barrel-sized bombs that are dumped from helicopters.

The Britain-based Syrian Observatory for Human Rights said it has documented at least 146 people including 29 children who were killed in government airstrikes in Ghouta since the beginning of the month.

President Bashar Assad, in an interview with the BBC earlier this week, denied that his forces were using a weapon called “barrel bombs,” a remark that sparked wide-scale outrage by supporters of the opposition.

Separately, most residents in opposition-held areas Aleppo favor the UN’s proposal of a “freeze” in fighting but are skeptical that a truce will hold, a survey published Thursday said.

The poll said 53 percent of people surveyed favored a lull in fighting, with 38 percent saying a freeze would allow humanitarian aid to reach war-torn areas of Syria’s second city.

Fewer than one in 10 respondents said a truce would expedite a political solution to Syria’s conflict, however.

The poll, conducted by the Sada Center for Research and Public Opinion and the Arab Reform Initiative, surveyed 975 people in opposition-held areas of Aleppo.

Eighty-nine percent of respondents said a freeze would either prove unworkable or unstable without rules binding the regime and opposition factions operating in Aleppo.

But most – 77 percent – did not have faith in the international community to be a trustworthy guarantor.