IS 'chemical bomb factory' destroyed in US-led attack in Iraq

US-led coalition jets destroyed a factory in Iraq used by the Islamic State group to make chemical weapons, the Pentagon said on Tuesday.

The converted pharmaceutical factory probably made chlorine or mustard gas, said Jeffrey Harrigian, a lieutenant general and commander of US forces in the Middle East.

"This represents just another example of Daesh blatant disregard for international law and norms," he told Pentagon reporters in a video call, using an Arabic term for IS.

The strike happened on Monday near Mosul and was conducted by fighter jets, ground-attack craft and a B-52 bomber, the Pentagon said. 

The US defence department has said IS uses chlorine and sulfur mustard weapons in Iraq and Syria.

Iraqi security forces, backed by coalition air forces, are in the final weeks of "shaping" operations before an expected assault on Mosul, which IS seized in 2014 and remains the group's last main stronghold in Iraq.