Iraq has informed the United Nations that the Islamic State extremist group has taken control of a vast former chemical weapons facility northwest of Baghdad where 2,500 chemical rockets filled with the deadly nerve agent sarin or their remnants were stored along with other chemical warfare agents.

Iraq's U.N. Ambassador Mohamed Ali Alhakim said in a letter to U.N. Secretary-General Ban Ki-moon circulated Tuesday that "terrorist" groups entered the Muthanna site June 11 and seized weapons and equipment from the protection force guarding the facility.

He singled out the capture of bunkers 13 and 41 in the sprawling complex, which according to a 2004 U.N. report also contained the toxic agent sodium cyanide, which is a precursor for the chemical warfare agent tabun, and artillery shells contaminated with mustard gas.