Al-Afari, who worked in Saddam Hussein's barbaric regime as a biological munitions specialist, was captured last month and is being interrogated at a temporary detention site in Erbil, Iraq.

The U.S. has confirmed they arrested a prominent ISIS leader. American officials told the New York Times that al-Afari admitted during interrogation that ISIS plans to use mustard gas in future attacks.

Al-Afari, who is thought to be in his early 50s, was captured in a raid by commandos last month near the northern Iraqi town of Tal Afar, officials said.

He used to work in Saddam regime before its downfall during the Iraq War and was ISIS chemical weapons chief until his capture.

Information provided by al-Afari has already led to a number of airstrikes on ISIS bomb making laboratories, with Special Forces operations targeting weapons experts on the ground, according to intelligence officials qouted by daily Mail.

The U.S. bombed 'improvised weapons facilities' near Mosul, Iraq, this week but has not revealed whether these were related to al-Afari's capture, CNN reported.

The terror network is said to have recruited a number of scientists from Saddam's toppled Baath regime.

Mustard gas causes the lungs and skin to blister has been used in attacks in Iraq and Syria by ISIS,(So-called Islamic state, ISIL , IS or Daesh) Nusra Front and other terrorist Group .

'More than a symbolic attack seems to me to be beyond the grasp of ISIS,' Dan Kaszeta, a former U.S. Army chemical officer and Department of Homeland Security expert, said.

'Furthermore, the chemicals we are talking about are principally chlorine and sulfur mustard, both of which are actually quite poor weapons by modern standards.'

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