Islamic State (IS) militants could be plotting First World War-style attacks using chlorine gas on Britain, a top chemical warfare expert in the world has warned, according to a media report.
Hamish de Bretton-Gordon, the retired head of chemical and biological weapons for the British Army and the North Atlantic Treaty Organisation (NATO), said that he feared an attack by returning jihadis using chlorine gas-filled IEDs to be "highly likely", the Daily Mirror reported on Sunday.
"This could happen on a train or tube or even at a big football match," he said.
"Acquiring weapons and ammunition is very difficult in Britain, but you can get up to 90,000 tonnes of chlorine without any licence.
"In a confined space if you saw this yellow and green gas cloud and started smelling it the panic would create carnage," he warned.
The chilling alert comes days after the 20th anniversary of the attack on the Tokyo subway in Japan in which extremists released the deadly gas sarin on several tube lines.
It follows increasing fears that IS militants are stockpiling chemical weapons for a bloody last stand against troops fighting to drive them out of Iraq.
Spies believe the ruthless IS leader Abu Bakr al-Baghdadi has ordered his followers to encourage an all-out attack in Europe.
Bretton-Gordon revealed that hundreds of crude chlorine IEDs -- which cause choking -- are now being used extensively by IS in the defence of the Iraqi city of Tikrit.
Iraqi security forces are convinced that chlorine bombs are being prepared to defend Mosul, Iraq's second city.
When IS overran Mosul last June, it seized a huge chlorine factory and Iraqi forces believe it is stockpiling material for a deadly last stand. There are also fears that IS has even deadlier mustard gas and sarin.
Bretton-Gordon said: "Islamic State are all over these chemical weapons. The big prize is Mosul, its capital in Iraq. Lose it and they lose the country and have to retreat to Syria."
The Daily Mirror has revealed that Britain's Special Air Service (SAS) forces in Iraq have been ordered to take chemical weapons suits.
An intelligence source said: "Islamic State definitely wants a spectacular (attack) in the West -- to build on fear it generated in the Charlie Hebdo attack in Paris."
"Its favourite place would be a transport hub, with footage of the aftermath likely to be broadcast on the internet spreading horror worldwide."
Next month is the 100th anniversary of the first use of gas in modern war. The German Army deployed chlorine at Ypres, killing 6,000 Allied troops, mainly from asphyxiation and lung damage.
