BEIRUT: World leaders called Thursday for an urgent cease-fire in Syria as government forces pounded the opposition-controlled eastern suburbs of the capital in a crushing campaign that has left hundreds of people dead in recent days.

The U.N. Security Council heard a briefing from U.N. humanitarian chief Mark Lowcock on what he called “the humanitarian disaster unfolding before our eyes” in the rebel-held suburbs known as eastern Ghouta.

Sweden and Kuwait were seeking a vote on a resolution ordering a 30-day cease-fire to allow relief agencies to deliver aid and evacuate the critically sick and wounded from besieged areas to receive medical care.

But Russia’s U.N. ambassador, Vassily Nebenzia, who called Thursday’s meeting, put forward last-minute amendments, saying the proposed resolution was “simply unrealistic.”

He also accused global media outlets of a massive disinformation campaign that ignored what he claimed were thousands of fighters, including al-Qaida-linked militants, that were shelling Damascus from eastern Ghouta and taking refuge in hospitals and schools.

Council members said they needed to study the Russian proposals.

“We will try and find a way forward that works for everyone,” Sweden’s U.N. Ambassador Olof Skoog told reporters, adding that a vote was likely on Friday.

In eastern Ghouta, medical workers said they hadn’t been able to see their families for days as they worked round the clock at hospitals that have been moved underground to protect them from bombing, while their spouses and children stay in shelters.

“You can’t be above ground for even 15 minutes,” said a nurse in the town of Kafr Batna, who spoke on condition of anonymity to protect the identity of family members still living in government areas. “At any moment I expect to have to treat my relatives for wounds,” he said.

In the background the deep boom of a bomb could be heard exploding as the nurse spoke by Skype to the Associated Press. He said a barrel bomb had fallen less than one-third mile away.

A spokesman for the Syrian Civil Defense search-and-rescue group said eastern Ghouta was being targeted for “extermination.”

“This is a war against civilians,” said the spokesman, Siraj Mahmoud. “The civil defense is being targeted as they rescue women and children, evacuate civilians from targeted areas and put out fires.”

Four rescue workers of the organization, also known as the White Helmets, have been killed since Sunday, Mahmoud said.

The Britain-based Syrian Observatory for Human Rights monitoring group said 400 people, including dozens of children, have been killed since Sunday.

Foreign Minister Sergey Lavrov said al-Qaida-linked fighters were using civilians as human shields in the rebel-held suburbs outside Damascus.

Al-Qaida’s Syria affiliate is not known to have many fighters in eastern Ghouta, and government forces on Thursday concentrated their fire on hospitals, ambulances, apartment blocks and other civilian sites, according to rescue workers, war monitors, human rights groups, and several videos emerging from the war-scarred region.