Woman and two children killed in suspected chlorine attack in Aleppo – one of dozens of such attacks reported since Syria gave up its weapons stockpile

A woman and two children have been killed and dozens injured in an alleged chlorine gas attack in Aleppo, doctors have said, as experts warned that the frequent use of chemical weapons in Syria risked normalising war crimes.

There have been dozens of attacks with chlorine gas since Syria officially agreed to give up its weapons stockpile following a 2013 sarin gas assault on a Damascus suburb, rights groups and doctors on the ground said.

The latest reports came as Russia offered to halt fighting for three hours a day to allow aid into besieged parts of the city, but the UN countered by saying it needed at least 48 hours a week to take convoys through heavily bombed and mined roads into eastern Aleppo.

There are still 1.5 million people living in Aleppo, the city that was Syria’s largest before the civil war and is now at the heart of the brutal battle for its future. he UN envoy to Syria, Staffan de Mistura, said about 300,000 civilians in rebel-held areas were at grave risk from water shortages and disease as fighting had intensified.

Asked about the chemical attack on the Aleppo district of Zubdiya, he said there was a lot of evidence that it took placeand it would constitute a war crime if chlorine gas was used, but he added that it was not his remit to verify the attack. “If it did take place, it is a war crime and as such it would require everyone … to address it immediately,” he said.

Last week, doctors in the neighbouring province of Idlib said they had treated more than two dozen patients following a suspected chlorine attack on the town of Saraqeb.

The challenge of verifying the use of chemical weapons in a war zone, particularly chlorine – which disperses rapidly and does not leave a unique chemical trace when used as a weapon – has hampered efforts to track their use.

However, a global chemical weapons watchdog, the Organisation for the Prohibition of Chemical Weapons, said it was confident that chlorine gas had been used as a weapon in past incidents.

It did not apportion blame but its a report into one attack that resulted in 13 deaths said 32 of the 37 people interviewed “saw or heard the sound of a helicopter over the village at the time of the attack with barrel bombs containing toxic chemicals”. The US ambassador to the UN, Samantha Power, tweeted in response that “only Syrian regime uses [helicopters]”.

The Syrian government denies using chemical weapons. Since the US president, Barack Obama, stepped back from enforcing his “red line” on their use, attacks have drawn nothing more than public condemnation from western leaders.

Although most recent attacks have been relatively small, the toll of dead and maimed civilians and activists is mounting and experts are concerned that the use of chemical weapons is no longer as shocking as it was a few years ago.

“There is certainly a huge risk of normalising [the use of chemical weapons],” said Richard Guthrie, a British chemical weapons expert who has raised concerns about the wider impacts of Syria’s continued use of toxins as weapons.

Facebook Twitter Pinterest A damaged vehicle after a Syrian army helicopter belonging hit a residential area in Aleppo with barrel bombs. Photograph: Anadolu Agency/Getty Images

“In recent decades, chemical weapons have slowly been de-legitimised as a currency of power. The continued reports of use of these abhorrent weapons are deeply concerning. This latest allegation of use is another contribution to the slow and steady diminishing of the taboo.”

Amnesty International and doctors on the ground said the timing of the attacks indicated they may be used as reprisals against civilians in areas where rebels make military gains. “There may also be a punishment angle to this,” said Neil Sammonds, Syria researcher with Amnesty. “Its beneficial for them to keep terrorising and making life as painful as possible for people living in areas they don’t control.”

The latest apparent attack happened after opposition fighters broke a siege on eastern Aleppo. Within hours, doctors said they were preparing for a chemical attack. Another chlorine attack reported this month was near where a Russian helicopter was shot down.

“Using chemical agents without accountability has become the new normal in Syria. It is a very dangerous precedent that the international community is setting,” said Zaher Sahloul, a Syrian-American doctor who regularly volunteers in Aleppo, l, whose organisation tracks reported chemical attacks.

“Since the UN security council resolution to destroy chemical weapon stockpiles in Syria, there were more than 70 attacks with chemical agents by the Syrian regime but this time with chlorine gas.”

The Syrian American Medical Society said nearly 1,500 civilians had been killed in chemical weapons attacks in Syria between December 2012 and October 2015, the majority in the attack on the Damascus suburb of East Ghouta.

Facebook Twitter Pinterest A rescue worker treating a baby allegedly affected by a chlorine gas attack in Saraqeb. Photograph: Motie Jalal / Syria Civil Defense/ Idlib/EPA

Most recent attacks attributed to government forces have used chlorine gas, which analysts say may be due to its ready availability as a common industrial chemical and the challenges of tracing it.

“[Chlorine], although militarily not a very efficient way of conducting war, is extremely effective at sowing terror. It’s also a very useful weapon if you don’t want to be traced,” said Jerry Smith, director of security consultancy RameHead International and a former UN chemical weapons inspector in Syria.

“So all you are left with after an attack is reporting and witness statements. And in an investigation, if you base everything on witnesses, some people will question if that is ever sufficient.”

Smith, who said chlorine had probably been used several times in Syria, believes the challenge of tracing the gas and the international community’s weak response may make it a particularly attractive weapon for regime forces.

“Its impact is two-fold, not only is it a terror weapon, but victims know it’s a terror weapon, and that regimes shouldn’t use it under international law. So that almost increases the impact of terror,” said Smith.

The impact of Syria’s use of chemical weapons could allow chemical weapons to flourish far beyond its own civil war, Guthrie has warned. “As it stands today, one lesson of Syria that could be drawn by other dictatorships is that a chemical weapons programme may buy you time within a civil war,” he told a recent international conference.

“If the major disincentives to producing chemical weapons and then to use them might be fear of being deposed by internal or external forces or getting caught by the international community and being brought to trial, then the Syria case has illustrated none of these.”