Nine members of the United Nations Security Council have requested an emergency meeting over a suspected chemical attack reported to have killed at least 70 people in Syria.
A joint statement by the medical relief organisation Syrian American Medical Society (SAMS) and the civil defense service, which operates in rebel-held areas, said 49 people had died in the attack in the town of Douma yesterday.
Others put the toll higher, with the Union of Medical Care and Relief Organizations, which runs medical facilities in the Eastern Ghouta, saying at least 70 people were confirmed killed.
According to the US-based Syrian American Medical Society, at least 48 people died, showing "symptoms indicative of exposure to a chemical agent".
More than 500 people were brought to medical centres with such symptoms, it said, quoting emergency services in Douma.
One video, recorded by rescue workers known as the White Helmets, showed a number of men, women and children lying lifeless inside a house, many with foam at their mouths.
Other unverified footage showed young children crying as they are treated in a makeshift medical unit.
The UK, France, the US, Poland, the Netherlands, Sweden, Kuwait, Peru and Cote d'Ivoire called an emergency meeting of the UN Security Council to discuss the reports of the chemical weapons attack.
The British mission to the United Nations tweeted the meeting was expected to be held sometime on Monday.
Douma is the last rebel bastion in the Eastern Ghouta region outside the capital, Damascus, following a government offensive and other evacuation deals brokered by Russia.
Syria and Russia denied a chemical attack took place.
In a series of tweets, US President Donald Trump described President Assad as an "animal".
Many dead, including women and children, in mindless CHEMICAL attack in Syria. Area of atrocity is in lockdown and encircled by Syrian Army, making it completely inaccessible to outside world. President Putin, Russia and Iran are responsible for backing Animal Assad. Big price...— Donald J. Trump (@realDonaldTrump) April 8, 2018
....to pay. Open area immediately for medical help and verification. Another humanitarian disaster for no reason whatsoever. SICK!— Donald J. Trump (@realDonaldTrump) April 8, 2018
Asked if the US might attack after Saturday's reported attack, White House homeland security adviser Tom Bossert told ABC television: "I wouldn't take anything off the table."
French President Emmanuel Macron has also threatened to strike Syria if the government used chemical weapons against civilians.
Mr Trump previously ordered an air strike on a Syrian air base after a similar chemical attack on the opposition-held town of Khan Sheikhoun which killed more than 80 people in April 2017.
The UN and the Organisation for the Prohibition of Chemical Weapons later found the Syrian government responsible for the attack on Khan Sheikhoun, saying Sarin gas was used.
UK Foreign Secretary Boris Johnson said on Sunday that the suspected chemical attack must be investigated urgently.
"We are in close touch with our allies following these latest reports," he said. "Those responsible for the use of chemical weapons have lost all moral integrity and must be held to account."
Russian talks with the rebels, the Jaish al-Islam group, broke down last week and fighting resumed.
However, according to Syrian state media, a deal was struck with Jaish al-Islam on Sunday to allow them to leave Douma within 48 hours in return for them freeing prisoners. The rebel group has not commented.
Syrian state media accused "terrorist" media of fabricating reports about a chemical attack in order to hinder the advance of government forces through the Eastern Ghouta.
Russia's foreign ministry said reports of a chemical attack by Syrian forces on Douma had been "planted" in order to create a pretext for a possible military intervention in Syria.
Iran's foreign ministry said the reports of a chemical gas attack were not based on facts and were being circulated so the United States and other Western countries would have an excuse to take military action.
"The purpose of these mendacious conjectures, which are without any basis, is to shield the terrorists and the irreconcilable radical opposition, which rejects a political settlement, while at the same time trying to justify possible external use of force," it said.
In seven years, the war has left more than 400,000 people dead or missing presumed dead, while more than half the population have been driven from their homes.
- BBC / Reuters