ISIS will use crude chemical weapons in the Battle for Mosul, Iraq, US officials have warned.
The terror death cult has already used poison gas against civilians and local forces.
Now hundreds of British and American troops on the ground could be at risk.
US forces – who have 5,000 troops on the ground in Iraq – have confirmed the jihadis used the agent in an attack earlier this month.
About 250 British squaddies are also in Iraq helping the Iraqi army and Kurdish Peshmerga forces.
Residents of Mosul revealed ISIS is using civilians as human shields as coalition forces capture outlying villages and advance on the jihadis” stronghold.
ISIS leader Abu Bakr al-Baghdadi is reportedly among thousands of hardline militants still in the city, suggesting the group is preparing to fight to the death.