Syrian army forces load a machine gun mounted at the back of a vehicle in the Syrian Christian town of Maalula.
Britain's definitive claims that the deadly gas sarin was used in Syria have been linked to a secret fact-finding mission.
A senior Syrian opposition leader has revealed that some of the victims of last month's alleged chemical attack in the country were secretly flown to the UK for medical tests.
According to a 'Sunday Times' report, Ahmad Asi al-Jarba, the president of the National Coalition for Syrian Revolutionary and Opposition Forces, has claimed that traces of sarin were found in up to three people hit by the attack in Ghouta, eastern Damascus, on August 21.
British Prime Minister David Cameron had told world leaders at the G20 summit in Russia last week that the British had confirmed sarin was used in the attack that claimed 1,400 victims, as part of his ongoing plea for international action against the Bashar al-Assad regime.
Syrian opposition coalition disclosed the secret tests and said its leadership was updated about the state of the victims during a visit to London last week.
Al-Jarba confirmed he was aware of a "small number" of victims who had been flown to the UK for treatment.
"The president was told [on Thursday] during a meeting that the results from the examinations confirmed traces of sarin gas on these individuals. They are in a stable condition but they found traces of sarin gas inside their systems," Hadi Albahra, the secretary of the political committee within the coalition, was quoted by the 'Times' as saying.
He added that there were "two or three" victims in the UK who were "from the Ghouta area" and that they would stay in Britain until "they are treated and well".
The Foreign and Commonwealth Office (FCO) said it could not confirm the Syrian statement, which came as it emerged that US strike aircraft have been banned from using British military bases for launching air attacks believed to be the first time such a restriction has been imposed since World War II.
US President Barack Obama has directed the Pentagon to develop an expanded list of targets in Syria.
Options include using B-52 bombers, which can carry air-launched cruise missiles, and B-2 stealth bombers.
However, military experts say the use of such bombers would be complicated by the US being prevented from using British bases.
Meanwhile, Obama stepped up his campaign to persuade a deeply sceptical America and reluctant Congress to back his call for "limited" strikes against Syria.