A pharmacist in the town of Arbeen who identified himself as Abu Ahmad said he attended to dozens of wounded people in a field hospital after the shelling on Zamalka and Ein Tarma early Wednesday. He said many were moved to Arbeen.
The bodies of 63 of the dead had signs of a chemical weapons attack, he said, though he could not confirm this.
"Their mouths were foaming, their pupils were constricted, and those who were brought in while still alive could not draw their breaths and died subsequently," he told The Associated Press via Skype. "The skin around their eyes and noses was grayish."
Activists in nearby Zamalka told Abu Ahmed that an additional 200 people died in that town on Wednesday.
Syria's information minister, Omran al-Zoubi, denied government troops used chemical agents, calling the activists' claim a "disillusioned and fabricated one whose objective is to deviate and mislead" the U.N. mission.
The head of the U.N. team, which has a mandate to investigate previous claims of alleged chemical attacks, said he wants to look into the latest claims. Speaking to Swedish broadcaster SVT, Ake Sellstrom said the high numbers of dead and wounded being reported "sound suspicious."
"It looks like something we need to look into," Sellstrom, who is Swedish, was quoted as saying.
He said a formal request from a member state would have to go through U.N. channels and Syria would need to agree — and there is no guarantee that it would.
French President Francois Hollande said the latest allegations "require verification and confirmation," according to government spokeswoman Najat Vallaud-Belkacem. Hollande said he would ask the U.N. to go to the site "to shed full light" on the allegations.
In addition to the U. S. and Britain, Germany, Turkey and the EU called for immediate U.N. access to the site of the alleged attack. The Syrian government did not immediately respond to the demands.
The U.N. Security Council held emergency consultations about the purported attack, and U.N. deputy spokesman Eduardo del Buey said Sellstrom's team was in talks with the Syrian government about all alleged chemical attack, including Wednesday's.
Mohammed Saeed, an activist in the area, told the AP via Skype that hundreds of dead and injured people were rushed to six makeshift hospitals in the eastern suburbs of Damascus.
"This is a massacre by chemical weapons," he said. "The visit by the U.N. team is a joke. ... (Assad) is using the weapons and telling the world that he does not care."
Photos posted on Facebook by an activist group in Arbeen showed rows of Syrian children wrapped in white shrouds, and others with their chests bare. There appeared to be very little sign of blood or physical wounds on the bodies.