The ISIS chemical weapons expert reportedly captured in a Special Forces raid last month was being held for interrogation at a new U.S. detention facility in Iraq, U.S. officials said Wednesday.

The makeshift jail for terror suspects, the first set up by the U.S. since the 2011 troop withdrawal, was reportedly in or near Irbil, capital of the autonomous Kurdish region, and was being used to hold Sleiman Daoud al-Afari, a top operative for the Islamic State in Iraq and Syria, or ISIS.

Iraqi officials said al-Afari formerly was an engineer specializing in chemical and biological weapons for the Military Industrialization Authority of the late Iraqi dictator Saddam Hussein.

Without describing the detention facility or its location, Navy Capt. Jeff Davis, a Pentagon spokesman, essentially confirmed its existence.

He said that a contingent of about 200 Special Forces troops, designated the Expeditionary Targeting Force (ETF) by Defense Secretary Ashton Carter, had already begun kill-and-capture missions in Iraq and Syria against ISIS leaders and a detention facility was a necessity for their operations.

"It's a capability that was put in there to conduct raids," Davis said of a place to interrogate captured suspects. "Part of conducting raids is detention of a very small number of detainees for very short period of time. And they would logically have the capability to conduct those missions."

Davis said terror suspects captured by the targeting force could be held indefinitely under the Law of Armed Conflict but he echoed Carter and other Defense and State Department officials in saying that the intention was to hold them for a short duration and then turn them over to the Iraqi government.

President Barack Obama has barred the transfer of any additional terror suspects to the detention facility at the Guantanamo Bay, Cuba, naval base.

Al-Afari, who reportedly headed the ISIS research branch for chemical weapons, was captured last month in a raid near the northern Iraqi town of Tal Afar, The New York Times and other outlets reported.

"We know that they have used chemical weapons on multiple occasions in both Iraq and Syria," Davis said of ISIS. Al-Afari was believed to specialize in preparing the agent sulphur mustard for delivery by artillery and rocket launchers. Davis said sulphur mustard was a powder and was distinct from mustard gas.

-- Richard Sisk can be reached at richard.sisk@military.com