Isis are conducting chemical weapons experiments on "human guinea pigs" before launching attacks on Western targets, according to secret documents.

The extremist group has reportedly poisoned prisoners by spiking their food and water with compounds used in pesticides that are easy to obtain

Security forces now fear the terror network may hatch a twisted plot to contaminate Western food supplies with formulas that quickly dissolve in liquid.

The experiments were recorded in a stash of papers found hidden in Mosul University after Iraqi special forces recaptured the city from IS fighters.

They reveal one victim was fed thallium sulphate - a colourless, tasteless salt that can be dissolved in water - and began to suffer fever, nausea, and swelling of the stomach and brain before dying in agony ten days later.

Isis described the chemical as an "ideal lethal poison" and claimed to be in “possession of an ample amount of the solution to fill demands”, according to the documents, which were verified by British and US forces and later obtained by The Times.

Terrorists also injected a nicotine-based compound, said to have no antidote, into another victim who passed out within seconds and died hours later.

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Ingredients for the poison are contained in cigarettes and vaping supplies, while thallium sulphate is available for sale in many countries including the US.

The chemical weapons report also contained recipes and guides for producing the toxic nicotine compound.

Chemical weapons expert Hamish de Bretton-Gordon told The Times: "This is a horrifying throwback to the Nazis who would test nerve agents on live humans. During the Second World War, the Nazis conducted thousands of deadly experiments with mustard gas on prisoners at Sachsenhausen concentration camp, near Berlin.”

Isis has recently lost territory in Mosul and now controls just one-tenth of the city following a surge by Iraqi forces in October.

In pictures: Isis' weapons factories Show all 11 1 /11 In pictures: Isis' weapons factories In pictures: Isis' weapons factories A mortar round fin manufactured by Isis in Gogjali, Mosul, November 2016 Conflict Armament Research In pictures: Isis' weapons factories Isis rocket components discovered in Gogjali, Mosul, Iraq in November 2016 Conflict Armament Research In pictures: Isis' weapons factories Isis mortars discovered near Karamlais, Iraq, in November 2016 CAR In pictures: Isis' weapons factories An Isis rocket launch frame in Qaraqosh, November 2016 Conflict Armament Research In pictures: Isis' weapons factories A memo from Isis' COSQC on quality control at a manufacturing facility in Gogjali, Mosul, November 2016 Conflict Armament Research In pictures: Isis' weapons factories Electrically-operated initiators manufactured by Isis in forces Gogjali, Mosul, November 2016 Conflict Armament Research In pictures: Isis' weapons factories Isis mortar tubes at a manufacturing facility in Karamlais, November 2016 Conflict Armament Research In pictures: Isis' weapons factories An Isis mortar production facility discovered in Gogjali, Mosul, in November 2016 Conflict Armament Research In pictures: Isis' weapons factories An Isis weapons manufacturing facilities near Mosul in November 2016 Conflict Armament Research In pictures: Isis' weapons factories Stocks of French-manufactured Sorbitol, Latvian potassium nitrate and Lebanese sugar at an Isis weapons factory in Iraq Conflict Armament Research In pictures: Isis' weapons factories A destroyed Isis weapons facility in Qaraqosh, Iraq, November 2016 Conflict Armament Research

They are thought to have used Mosul University, one of the largest in the Middle East, to develop chemical weapons for the last three years.