Islamic State used Mosul university to make chemical weapons

The militant group, which used the institution as a headquarters during its two-and-a-half-year rule of the city, held chemicals at the site which were mixed to make weapons to be used in the ongoing conflict.

Tests that were run by Iraqi authorities proved positive results for sulphur mustard, Pentagon spokesman Navy Captain Jeff Davis said. 

Mosul university was "central to the ISIS chemical weapons program," Davis said, using an IS acronym.

"They have received positive samples; that is indeed what was going on there."

Davis said he was not aware of anyone having been killed by the chemicals but confirmed "it was used primarily as an irritant and something to scare people," he said. 

More than three months into a offensive by Iraqi government troops and US-led allied forces, IS militants have been driven from the eastern half of the city of more than a million people, but remain in control of the west.

The latest revelations come as the United Nations officials said removing mines, explosives and booby traps left by Islamic State forces in Iraq's Mosul could cost $50 million.

Costs for Iraq as a whole were previously estimated at $50 million this year, but this could double because of Mosul, the UN Mine Action Service (UNMAS) said.

"Looking at the contamination in Mosul we will need $50 million and $50 million for the rest of the country," Paul Heslop, chief of UNMAS programme planning and management section, told Reuters.

"Clearing IEDs and building clearances is a lot more dangerous than minefields. You need a higher level of technical skill and complex equipment and it's slower. As areas are liberated, you get a better idea of the level of contamination," he said.