Islamic State has acquired a cache of deadly chemical weapons in Libya which pose a significant threat to European security, a British expert has warned.

According to Middle East reports, the terror group has unconfirmed quantities of sarin and mustard gas after defeating government forces in southern and central Libya.

Former British Army officer Hamish de Bretton-Gordon told The Mail on Sunday that the weapons remain dangerous, even though they are likely to be ten years old, and in a degraded state.

Mr de Bretton-Gordon based his warning on President Assad’s use of one tonne of sarin in Ghouta, Syria, in August 2013, which killed as many as 1,000 people.

Islamic State has acquired a cache of deadly chemical weapons in Libya, an expert warned. Pictured, shells contained mustard gas near the southern Libyan town of Waddan in 2011

Speaking from the Gulf, where he advises the Iraqi government on chemical weapons, he said: ‘We saw what a single ton of not very good quality sarin did in Ghouta.

‘While we don’t know how much IS has acquired, and though the Libyan sarin dates back to the Gaddafi era, it would still have a toxicity and pose a danger.

‘Libya is virtually Europe and so the fear factor from a European perspective is huge. I should think the security forces will be watching this situation very closely.’

IS has used chlorine as a weapon in Iraq and has acquired significant expertise in chemical warfare from those who previously developed chemical weapons for Saddam Hussein.