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The plan was uncovered by German police who stumbled across documents as they searched a refugee camp for the Berlin truck killer. These detailed chemical agents and the names of British towns. But the suspect, aged in his early 30s, had disappeared and it is feared he could now be in the UK. Sources say he was trained in toxins by the Assad regime and was being tracked by US agents before giving them the slip.

GETTY Intelligence agencies are hunting for a Syrian scientist posing as a refugee

The news emerges just days after security minister Ben Wallace warned Britain to prepare for a “mass casualty attack” which may involve chemical weapons. Last week, Britain’s most senior fire chief warned that the potential for a terrorist chemical attack in the country is a “huge concern”. The alarm was raised on December 20, when counter-terror police raided Berlin’s defunct Tempelhof airport, now the site of the country’s largest refugee camp, following the Berlin terror attack on the previous day. As more than 250 officers ransacked the camp in their search for the attacker, they discovered a document with details about a separate plot in Britain.

GETTY The plan was discovered by German police while searching for the Berlin truck killer

The document, which was partially charred, contained details of chemical agent and listed two English towns.

The contents were of such significance that MI5 were immediately contacted Intelligence source

“The contents were of such significance that MI5 were immediately contacted,” said an intelligence source last night. Security services were last night scouring both targets, one of which was described only as “a seaside on town on the south coast”. British Intelligence sources confirmed they had already been warned by US counterparts about the possibility of a Syrian scientist posing as a refugee.

GETTY German police immoediately informed MI5 of the plot due to the seriousness of the discovery

US spies had been tracking the suspect, trained under the Assad regime, after he left Damascus. However, the trail went cold. However, the camp discovery showed he had travelled further into Europe than had been previously thought. Last night officials with Germany’s Ministry of the Interior said: “We can neither comment on ongoing investigations nor on the details of our intelligence services’ operations.” The scientist is thought to have been trained by the Assad regime. He is said to have played a key role in chemical attacks launched by President Bashar Assad on his own people.

It is believed that he has either gone rogue and is now working for fundamentalist groups against Assad – or that he is part of a ‘false flag’ operation arranged by the dictator so that a terror outrage can be blamed on Islamic State. The scientist is not thought to have any covert training, fuelling the belief that he is arranging to meet sympathisers already here. “Our US counterparts have been instrumental in tracking this individual. I can say that the net in closing in,” added the source. It is feared that his chemical expertise goes far beyond the homemade Chlorine-based mustard gas used by IS in the past. In 2013 Coalition forces destroyed 600 tonnes of chemical agents used by Assad to manufacture Sarin and mustard gas.

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He sanctioned the use of Sarin in 2013 during an attack against opposition forces in Ghouta, Death toll estimates range from 281 – 1,791 civilians. The possibility that his actions are being directly sponsored by the Assad regime, with the intention of showing that IS has access to very sophisticated chemical agents, is “very real”, analysts warned last night. “It is certainly possible that this scientist’s actions could be directed by the regime,” said Kyle W Orton, Research Fellow and Syria analyst with the Henry Jackson Society think-tank. “From the very beginning, Assad’s aim has been to enlist the West as at least a tacit partner by transforming the conflict into a binary one between himself and Islamist terrorists, and he has worked to empower jihadists, including IS, to achieve this.

GETTY British Intelligence services revealed that they had been warned of the Syrian scientist by the US