French and British officials have both announced that tests confirm the use of sarin gas by the Syrian government.

France’s foreign minister appeared on French television and expressed “no doubt” over the results:

“There is no doubt that it’s the regime and its accomplices” that are responsible for use of the gas,French Foreign Minister Laurent Fabius said on France 2 television. “All options are on the table,” he added. “That means either we decide not to react or we decide to react including by armed actions targetting the place where the gas is stored.”

Similar conclusions were reported in Britain:

According to a Foreign Office spokesman, Britain “has obtained physiological samples from inside Syria which have tested positive for the nerve agent sarin”. The UK statement added: “There is a growing body of limited but persuasive information showing that the regime used – and continues to use – chemical weapons” in Syria.

French reporters were credited with smuggling samples out of Syria for the testing.

Meanwhile the United States has continued to caution that more proof is needed, with offifials calling for more evidence. Asked how long compiling such evidence might take, officials declined to provide a timetable.

German scientists invented sarin in the 1930s as a pesticide before passing its formula to the Nazis at the start of World War II. But sarin – which is over 20 times more lethal than cyanide – was not used in conflict until Saddam Hussein’s 1988 bombardment of the city of Halabja. Some 5,000 Iraqi Kurds were killed in the attacks.

The chemical was also used in the 1994 and 1995 subway attacks by members of two Japanese cults that killed 21 people and injured more than 1,000.