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.”