US Special Forces have captured a former official with the Saddam Hussein regime that went on to became the chemical weapons chief for the Islamic State (Isis), according to Iraqi intelligence sources. Sleiman Daoud al-Afari was apprehended during a raid in February, two senior Iraqi intelligence officials told AP.

Under the Saddam's regime, Al-Afari reportedly worked at the Military Industrialization Authority that focused on the development of chemical and biological weapons. A number of Baathists and other former Hussein loyalists played a key role in IS (Daesh)'s rise in Iraq, providing critical assistance when conquering large parts of the country in a lightning campaign in 2014.

Since then, the jihadi group is known to have used chemical weapons in Iraq and Syria, albeit on a small scale. In February, Kurdish authorities said dozens of their Peshmerga fighters fell ill after an improvised rocket likely loaded with chlorine hit their positions near the northwestern town of Sinjar.

According to the Iraqi officials, al-Afari, an engineer in his 50s, held a senior role within IS as the head of its chemical weapons branch. He was captured during a raid in the northern town of Tal Afar, near Mosul.

Last month, Washington said a commando unit a captured an IS operative in Iraq but didn't release the man's identity. During questioning he revealed the jihadi group has developed a rudimental method to weaponized mustard gas by loading it in powder form into artillery shells, according to the New York Times.

Al-Afari is the first important scalp taken by a new Special Operations force deployed by the Obama administration to the Iraq with the specific task of snatching high-ranked jihadists. His capture is the last in a series of recent blows to IS hierarchies.

On March 8 the Pentagon said one of the group's top military commanders, the Chechen Omar al-Shishani, was targeted in an airstrike and possibly killed. Days earlier Amr al-Absi, a senior militant that became infamous as IS "kidnapper-in-chief" was reported dead in an airstrike near Aleppo.