The foreign minister of France on Tuesday accused the Syrian government of attacking its people with chemical weapons at least 14 times since October, with the most recent instance just a few weeks ago.
Laurent Fabius made his statement the same day as a Human Rights Watch (HRW) issued a report which said is there strong evidence the Syrian regime used chlorine gas on rebel-held neighborhoods last month, dropping the canisters in crude bombs on residential areas.
Speaking to reporters in Washington, Fabius cited "credible witnesses" to the attacks, which he said included the use of chlorine gas. He said it has been difficult to acquire definitive proof because chlorine gas generally evaporates too quickly to collect samples.
Fabius described the 14 attacks since last Oct. 25 as "small-scale" and not likely to spur a Western military response.
His statement and the HRW report add to growing concerns that chemical weapons are still being used in Syria months after an international deal to remove the country’s chemical weapons was reached following a sarin gas attack that killed hundreds of civilians last August.
Under the threat of U.S. airstrikes, Assad agreed to dismantle his chemical weapons program. Currently, a joint mission by the U.N. and the international chemical weapons watchdog says that 92 percent of Syria's stockpile has been shipped out of the country to be destroyed at sea.
But Fabius said that Syrian facilities that produce chemical weapons have not been destroyed, and he accused Assad's government of not being fully forthcoming with the West about its continued ability to use toxic chemicals against opponents.
HRW said forces loyal to Assad likely used chlorine gas on three towns in northern Syria in mid-April, according to interviews with 10 witnesses, video footage and photographs.
"Evidence strongly suggests that Syrian government helicopters dropped barrel bombs embedded with cylinders of chlorine gas on three towns," the group said. "These attacks used an industrial chemical as a weapon, an act banned by the international treaty prohibiting chemical weapons that Syria joined in October 2013.”
In late April, the Organization for the Prohibition of Chemical Weapons (OPCW), a United Nations watchdog that won the Nobel Peace Prize for taking the lead to remove Syria’s stockpile last year, said it would investigate the new chlorine claims, but it has not commented further on the issue.
In one incident, the Syrian government blamed an Al-Qaeda-linked group, the Nusra Front, for using chlorine gas on civilians in the rebel-held town of Kfar Zeita. It has not commented on other attacks. An extensive Associated Press investigation in late April found consistent claims that chlorine gas had been used in Kfar Zeirta.
HRW said testimony from eye-witnesses indicated that chlorine canisters were embedded into crude explosive-laden barrels, which military helicopters dropped at the time on rebel-held areas.
In Syria, only the pro-government forces have military aircraft, not opposition fighters. And though chlorine gas canisters are widely available, HRW said their use as a weapon is prohibited under international law.
The use of chlorine gas in bombs is not very effective as a weapon to kill people. However, HRW said it appeared the Syrian military was using the chlorine to terrorize residents into believing they had been gassed, even if many of the victims were not killed.
The fresh chemical weapons claims against Syria come as international aid workers and officials said this week that U.N. aid deliveries that started flowing into the country seven weeks ago have had questionable effectiveness.
The convoy of 78 trucks taking food, bedding and medicine to Syria's mainly Kurdish Hasakah province from southern Turkey was seen as a test of the willingness of Syria's authorities and rebels to abide by a U.N. resolution urging them to let aid across front lines and borders by the most direct routes.
But no distribution lists have been made available for this or any other U.N. delivery since the resolution, aid workers in Gaziantep near the Turkish border say, hampering the efforts of multiple NGOs trying to coordinate a response to the world's biggest humanitarian crisis.
"We still don't know where it went and we're not comfortable with this. The U.N. is constrained by the [Syrian] regime," said a Turkish official, speaking under condition of anonymity as his government has not taken a public stance on the issue.
Syria's civil war has killed more than 150,000 people over the course of three years, with more than 9 million in need of humanitarian assistance. The complicated patchwork of fighting has made aid distribution difficult.
The U.N. estimates 3.5 million of the people in need of aid live in areas that are taxing or impossible to reach for humanitarian workers, including more than 240,000 people besieged by government or opposition forces.
The convoy, dispatched over a largely deserted frontier to a region controlled by forces loyal to Assad, was meant to be a test case to show that the issue of access can be dealt with under the U.N. resolution. But there were doubts from the outset over whether assistance would reach those in rebel-held areas.
According to stipulations set by the Syrian government, the delivery was passed to Syrian partner agencies including the Syrian Arab Red Crescent.
Reuters asked the United Nations in Damascus for information on the final distribution of aid in Hasakah, but was told no one was available to speak. The Syrian Arab Red Crescent could not be reached for comment.
The U.N. resolution, adopted by the Security Council in February in a rare show of unanimity on Syria, sought to boost humanitarian access and threatened to take "further steps" if Syria's government and the rebels failed to comply.
Al Jazeera and wire services