Germany's foreign intelligence agency BND has collected evidence of mustard gas use by the Islamic State (IS) extremist group, a report in the German daily Bild said on September 7.
The newspaper said BND intelligence agents collected blood samples from Kurds who were injured in clashes with IS.
It quoted BND chief Gerhard Schindler as saying that the agency has "information that IS used mustard gas in northern Iraq."
Schindler said that the mustard gas either came from old Iraqi stockpiles produced under Saddam Hussein's rule or was manufactured by IS after it seized the University of Mosul.
Schindler's comments were confirmed to the Associated Press by a senior German intelligence official.
U.S. Defense Department spokeswoman Elissa Smith said that "while we will not comment on intelligence or operational matters, let us be clear: Any use by any party...of a chemical as a weapon of any kind is an abhorrent act.
"Given the alleged behavior of [IS] and other such groups in the region, any such flagrant disregard for international standards and norms is reprehensible," Smith said.