Forces loyal to President Bashar Assad used chemical weapons-laced mortars in a Damascus neighborhood Saturday, injuring dozens, the Syrian Observatory for Human Rights claimed.

Dozens of people were being treated for respiratory difficulties following the attack, according to reports carried by the Saudi-owned Al Arabiya TV channel.

The channel also reiterated reports by the BBC Thursday that chemical weapons were used in Saraqib in Idlib province on April 29. Two helicopters dropped devices on the town, which is located southwest of Aleppo, as it came under bombardment from regime forces, the report said.

Adding new details to the reports of that Saraqib attack, doctors at a local hospital said that they treated eight people who had breathing problems or constricted pupils. One woman, Maryam Khatib, died of her injuries, while her son Mohammed  was injured when he rushed to attend to her. A doctor who treated Khatib said her symptoms were similar to poisoning caused by organophosphates, ingredients used in nerve gases and insecticides.

Her son told the BBC’s Ian Pannell that there was a “horrible, suffocating smell” and that he lost his eyesight for three or four days. The following edited video purports to show the aftermath of the mortar attack in the city.

Meanwhile, the Syrian opposition claimed it killed four Iranian men in an attack on their convoy on Friday, as well as seven Hezbollah gunmen who had joined Assad forces in the city of al-Qusayr in Homs province.

Eighteen Hezbollah men were killed in that city last month.

On Wednesday, UK Under Secretary of State Wendy Sherman stated that chemical weapons had been used in at least two attacks in Syria.

The US government has intimated that the use of chemical weapons by the Syrian regime against its own people would potentially constitute the crossing of a “red line” for possible military intervention. Still, US President Barack Obama claimed two weeks ago that the intelligence about the use of chemical weapons in Syria was insufficient.

The Syrian government and opposition forces have both blamed each other for an attack in Aleppo in March and another in Homs in December 2012 in which chemical weapons were allegedly used.

Earlier in May the UN panel looking into war crimes in Syria backed down from a claim it had made that rebel forces used chemical weapons.

Syria has asked the UN to investigate only the Aleppo attack, whereas UN Secretary General Ban Ki-moon insists on investigating both incidents, creating a sticking point that has so far prevented an inquiry from proceeding.

The UN estimates that the two-year Syrian war has claimed over 80,000 lives, with the Syrian Observatory for Human Rights putting that figure at 94,000.

Stuart Winer contributed to this report.