US President Donald Trump has lashed out at Syrian President Bashar al-Assad and his allies Russia and Iran over a suspected chemical attack, saying there will be a “big price to pay”.
Scores of people are said to have been killed in an attack on the rebel-held town of Douma on Saturday.
The UK called for an urgent inquiry while Pope Francis said nothing could justify using chemical weapons.
In a series of tweets, Trump described Assad as an “animal”.
Both Syria and Russia deny a chemical attack took place.
And the head of the United Nations said on Sunday he was “particularly alarmed” by the alleged use of chemical weapons against civilians in Syria, during an attack that rescue workers said killed dozens of people.
Secretary-General Antonio Guterres said in a statement that he was “deeply concerned” about renewed violence in the city of Douma, citing reports that sustained airstrikes and shelling had killed civilians, destroyed infrastructure and damaged health facilities.
“I’m alarmed by allegations that chemical weapons have been used against civilian populations in Douma,” the statement said.
While noting that the UN was not in a position to verify such reports, Guterres said any confirmed use of chemical weapons would be “abhorrent.”
The attack came after Russian talks with the rebels, the Jaish al-Islam group, broke down last week and both sides resumed fighting.
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.
Douma is the last rebel bastion in the Eastern Ghouta region outside Damascus following a government offensive and other evacuation deals brokered by Russia.
Earlier, the US state department said the attack, if confirmed, called for an “immediate response by the international community”.
It has not been possible to verify independently what actually happened, or the number of dead.
The Union of Medical Relief Organisations, a US-based charity that works with Syrian hospitals, told the BBC 70 deaths had been confirmed by the Damascus Rural Specialty Hospital.
A spokeswoman said there were reports of people being treated for symptoms including convulsions and foaming of the mouth, consistent with nerve or mixed nerve and chlorine gas exposure.
However, the UK-based Syrian Observatory for Human Rights said 11 people had died of suffocation, adding that it could not say if chemical weapons had been used.
A video by rescue workers known as the White Helmets shows several men, women and children lying lifeless inside a house, again, many with foam at their mouths. Other unverified footage shows children crying as they are treated in a makeshift medical unit. —BBC & AFP