Syrian opposition activists said Wednesday that President Bashar al-Assad's forces used poison gas once again in the Damascus suburb of Harasta, Al Arabiya News Channel reported.
Footage of four men being treated by medics was posted on the internet. A voice off-screen gave the date and said Assad's forces used "poison gas in Harasta." It did not say if there were fatalities.
The face of one of the men appeared to be covered in vomit. He was shown shaking and moaning as doctors treated him. The voice off-screen said chemical weapons were also used in Harasta on Friday.
Activists said the chemical attack was the fourth that has been reported this month.
Last week, the Syrian opposition reported another attack in the Harasta neighborhood. The Shaam News Network said that at least 100 residents were in critical condition.
The opposition Syrian Coalition issued a statement condemning the alleged attack using "poison gas and highly concentrated pesticides."
"Assad is dragging his feet over the elimination of the chemical weapons arsenal, missing a series of deadlines while at the same time spraying people with gas on a scale- he thinks- small enough to avoid world condemnation," said Badr Jamous, Syrian Coalition Secretary General, in the statement.
White House spokesman Jay Carney said the U.S. was working with the Organization for the Prohibition of Chemical Weapons (OPCW) to check on whether the Syrian government was abiding to the 2013 deal on the destruction of Syria's chemical weapons stockpile.
Members of the Syrian opposition have in recent months accused Assad's regime of using chemical arms in a number of attacks including in the two Damascus suburbs of Harasta and Jobar.
U.S. and British officials are reportedly investigating claims that Assad's forces have used chemical weapons in at least four attacks around Damascus between January and April.
A U.N. inquiry found in December that sarin gas had likely been used in Jobar in August and in several other locations, including in the rebel-held Damascus suburb of Ghouta, where hundreds of people were killed.
The inquiry was only looking at whether chemical weapons were used, not who used them. The Syrian government and the opposition have each accused the other of using chemical weapons during the three-year-old civil war. Both sides have denied it.
The Ghouta attack caused global outrage and a U.S. threat of military strikes, dropped after Assad pledged to destroy his chemical weapons arsenal.
But the Syrian government failed to meet the Feb. 5 deadline to move all of its declared chemical substances and precursors, some 1,300 tonnes, out of the country. Syria has since agreed to remove the weapons by late April.