A Syrian rescue service operating in rebel-held territory said on Tuesday a helicopter dropped containers of toxicgas overnight on a town close to where a Russian military helicopter had been shot down hours earlier.
The opposition Syrian National Coalition (SNC) accused President Bashar al-Assad of being behind the attack. Assad has denied previous accusations of using chemical weapons.
A spokesman for the Syria Civil Defence said 33 people, mostly women and children, were affected by the gas, which they suspect was chlorine, in Saraqeb, in rebel-held Idlib province.
The group, which describes itself as a neutral band of search and rescue volunteers, posted a video on YouTube apparently showing a number of men struggling to breathe and being given oxygen masks by people in civil defence uniforms.
“Medium-sized barrels fell containing toxic gases. The Syrian Civil Defence was not able to determine the type of the gas,” said the spokesman.
The Syrian government and its Russian allies were not immediately available for comment.
Later, state news agency SANA said rebels had fired rockets armed with toxic gas on the government-held old quarter of Aleppo city, killing five people and causing eight breathing difficulties. It gave no further details. Rebels have denied previous accusations of using chemical weapons.
Russia is denying claims from Syrian rebels and human rights groups that it was behind a reported chlorine gas attack Tuesday in the same area where a Russian helicopter was shot down a day before, according to a Russian state media report.
“I don’t have information; we don’t have information about how the operation is proceeding,” Russia’s TASS news agency reports Kremlin spokesman Dmitry Peskov as saying. “It is very hard to react to such information releases: it is not always clear what they are based on, what their sources are and so on.”