Iraqi officials say man is Sleiman Daoud al-Afari, who specialized in chemical and biological weapons in Saddam Hussein's Military Industrialization Authority

US special forces captured the head of the Islamic State militant group's effort to develop chemical weapons in a raid last month in northern Iraq, two senior Iraqi intelligence officials have told the Associated Press, the first known major success of Washington's more aggressive policy of pursuing the jihadis on the ground.

The Obama administration launched the new strategy in December, deploying a commando force to Iraq that it said would be dedicated to capturing and killing Isis leaders in clandestine operations, as well as generating intelligence leading to more raids.