British Prime Minister David Cameron said lab tests conducted by the UK confirmed the use of sarin gas in the alleged Syrian chemical weapons attack in August.
Cameron spoke while at the G20 summit, which has been overshadowed by the current crisis in Syria.
He told the BBC that researchers at Porton Down labs had been "examining samples" from Damascus, where the alleged attack tool place on Aug. 21.
Cameron added that he took "full and personal responsibility for the decision to recall parliament, for the decision to take a strong and principled stand against the gassing of children in Syria."
The Guardian reported that the results showing sarin were from samples including clothes and soil collected from the Ghouta region. The samples the UK tested are different from the samples tested by the United States, the results of which were released by Secretary of State John Kerry earlier in the week.
Cameron said, "I don't think anyone is seriously denying that a chemical weapons attack took place. I think the Russians accept that. Even the Iranians accept that." He said the issue now would be convincing countries that Syrian President Bashar al-Assad's regime was responsible for the attack.
Porton Down military labs concluded the samples, taken from a patient who was treated after the attack, were unlikely to be fake, according to CNN.
Cameron took a jab at the Labour party, saying he regretted that they had chosen "the easy and the political path" over "the right and the difficult path." He said not doing anything would send an "appalling signal" to Assad and other dictators.