The Islamic State extremist group has taken control of a vast former chemical weapons facility northwest of Baghdad, where remnants of 2,500 degraded rockets filled decades ago with the deadly nerve agent sarin are stored along with other chemical warfare agents, Iraq said in a letter circulated at the UN.
The US government reported the takeover of the facility on June 20, and played down the threat, saying there were no intact chemical weapons.
Iraq's UN Ambassador Mohamed Ali Alhakim confirmed to Secretary General Ban Ki-moon in a letter on Tuesday that "armed terrorist groups" entered the Muthanna site on June 11 and detained the facility's guards. The following morning, the facility's project manager spotted the looting of some equipment via the surveillance system.
Islamic State, which controls parts of Syria, sent its fighters into neighbouring Iraq last month and quickly captured a vast stretch of territory straddling the border.
Alhakim said that as a result of the takeover of Muthanna, Iraq was unable "to fulfil its obligations to destroy chemical weapons" because of the deteriorating security situation. He said it would resume its obligations "as soon as the security situation has improved and control of the facility has been regained".
Alhakim singled out the capture of bunkers 13 and 41 in the sprawling complex 55 kilometres northwest of Baghdad.
The last major report by UN inspectors was released in 2004. It said bunker 13 contained 2,500 sarin-filled 122mm rockets produced before 1991, and about 180 tonnes of sodium cyanide, "a very toxic chemical and a precursor for the warfare agent tabun".
It said the sarin munitions were "of poor quality" and "would largely be degraded after years of storage under the conditions existing there". It said the tabun-filled containers were all treated with decontamination solution and likely no longer contained any agent, but "the residue of this decontamination would contain cyanides, which would still be a hazard".
According to the report, bunker 41 contained 2,000 empty artillery shells contaminated with the chemical agent mustard and 605 one-tonne mustard containers with residues. It said the shells could contained mustard residues which could not be used for chemical warfare but "remain highly toxic".