The Iraqi air force has taken delivery of two more F-16 fighter jets, bringing to six the number of the sophisticated U.S. planes it now has, an official said Wednesday.

The Iraqi air force has taken delivery of two more F-16 fighter jets, bringing to six the number of the sophisticated U.S. planes it now has, an official said Wednesday.

Baghdad-based U.S. military spokesman Colonel Steve Warren said the Iraqis had purchased a total of 36 F-16s, and the only thing holding up their delivery was the availability of trained Iraqi pilots.

"The limiting factor has been pilot generation," he told Pentagon reporters in a video call, noting that the US-trained pilots need to go through a year or more of instruction in Arizona.

"We bring the F-16s in as pilots are available," he added.

The United States sees the strengthening of Iraq's small air force as a key component in Baghdad's efforts to push back the ISIL group.

Warren said the Iraqi air force had been striking pre-planned targets but is also being used in a limited way to help troops on the ground.

"We look forward to this additional capability along with the additional trained pilots," Warren said.

Iraq took delivery of the first four F-16s in July.