Victims of a deadly chemical attack in Syria last month were flown to Britain for tests that revealed traces of the deadly nerve gas sarin in their systems, a British newspaper said Sunday.

Citing a Syrian opposition figure, Britain’s Sunday Times reported that either two or three people hurt in the attack — which the US and some of its allies have been attributing to the regime of Syrian President Bashar Assad — provided sufficient evidence to identify the chemical agent deployed.

Hadi Albahra, an official with the National Coalition for Syrian Revolutionary and Opposition Forces, told the paper that British Prime Minister David Cameron was apprised of the results of the tests conducted on the Syrian survivors.

“The president [of the coalition] was told [on Thursday] during a meeting that the results from the examinations confirmed traces of sarin gas on these individuals,” Albahra was quoted as saying. “They are in stable condition but they found traces of sarin gas inside their systems.”

The Obama administration says over 1,400 people were killed in that attack, which has proven pivotal in terms of the prospect of increased Western involvement in the two-and-a-half-year civil war.

As US President Barack Obama sought to persuade world leaders of the necessity of armed intervention in response to the chemical attack, Cameron on Thursday said that the United Kingdom had fresh evidence that was being examined at British laboratories.

Meanwhile, the Daily Mail reported that between 2004 and 2010, the British government issued licenses to sell sodium fluoride, an essential component of sarin gas, to Assad.

Cameron’s hasty decision to rule out action in Syria following a parliamentary vote last week rejecting intervention was taken to mean that Britain would not get involved even if the Assad regime would carry out an additional chemical weapons attack or new evidence emerged.

Still, US Secretary of State John Kerry, who met with more than two dozen European foreign ministers on Saturday, insisted that international backing to take strong action against Assad’s regime was growing, not receding.

Kerry noted that the ministers, who held an informal meeting of the European Union in Vilnius, Lithuania, made powerful statements condemning the attack, and that increasingly there was a sense of conviction that Assad was to blame. Kerry said the US had agreed to provide additional information to those ministers who were not yet convinced that Assad orchestrated the attack.

CNN on Saturday published video footage of the attack it said the administration had shown to lawmakers as part of its campaign to convince them of the necessity of a limited bombing campaign in Syria.

The EU endorsed a “clear and strong response” to a chemical weapons attack but didn’t indicate what type of response they were backing. It also said that evidence strongly points to the Syrian government. Still, the EU urged the US to delay possible military action until UN inspectors report their findings.

The Europeans were divided on whether military action would be effective. Britain’s Parliament has voted against military action. France had been ready to act last week but held off when Obama declared that he would seek the backing of Congress. French President Francois Hollande’s announcement appeared to catch French Foreign Minister Laurent Fabius off guard.

Earlier on Friday, Fabius told EU foreign ministers that there was no need to wait for the UN report because it would simply confirm what was already known — that the chemical weapons attack had occurred — but would not say who was responsible.

Hollande indicated Saturday that the UN report could be ready in a matter of days, and he would then be prepared to make a decision on a French intervention.

“I said … that I wanted to wait for the inspectors’ report, which I know will be ready within a very reasonable time period, that is, not that far from the decision of the US Congress,” he told French television after meeting with Lebanese President Michel Suleiman in Nice, France. “So, at that moment, I’ll have all the necessary elements that will let me tell the French people the decision I have made for France.”

However, Martin Nesirky, chief UN spokesman, insisted that there would be no preliminary report.

The report on the August 21 attack will be given to the UN Security Council and other member states once the lab analysis is complete, Nesirky said.

“We are not saying when that will be, except as soon as feasible,” he told The Associated Press. “This is a scientific timeline, not a political timeline.”