A top United States Air Force commander said that they have bombarded an Islamic State chemical weapons plant that was housed in a converted Iraqi pharmaceutical factory.

Air Force Lt Gen Jeffrey Harrigian said that 12 aircraft in all were used to hit the facility, which also served as IS headquarters, at 50 different points, reports the CNN.

He said, 'We don't know for sure at this point, what chemicals were involved' adding that the attack on the IS chemical facility took place on Monday in the vicinity of Mosul and the aircraft involved included F-15s, A-10s, F-18s, F-16s and a B-52.

The strike follows a United Nations-backed report issued last month that found that both the regime of Syrian President Bashar al-Assad and the IS have used chemical weapons in the five-year-long war.

At the time, National Security Council spokesman Ned Price had said the US-led anti-IS coalition had placed 'a high priority on targeting IS chemical weapons capabilities'.