United Nations ? U.N. weapons inspectors discovered a potentially hazardous chemical warfare agent that was taken from an Iraqi chemical weapons facility 11 years ago and mistakenly stored in their offices in the heart of midtown Manhattan all that time, officials said Thursday.

The material – identified as phosgene, a chemical substance used in World War I weapons – was discovered Aug. 24. U.N. and U.S. officials said the material posed no threat to anyone’s health or safety.

A team of hazardous materials experts from the FBI and New York City police removed the substance from the office on Manhattan’s east side, about a block north of U.N. headquarters, in three steel containers. The containers were flown to a military facility in Aberdeen, Md., for disposal, U.N. officials said.