A United Nations office was on Thursday evacuated following the discovery of vials suspected to have contained the poison gas phosgene.

UN spokeswoman Marie Okabe told media persons that the material had been taken from the al-Muthanna chemical weapons plant north of Baghdad and that the sealed samples had been there since 1996.

Okabe added that while winding down their activities, inspectors from the United Nations Monitoring, Verification and Inspection Commission (UNMOVIC) had discovered what had been identified a day earlier as a gram quantity of certain liquid substances, including phosgene, which could be 'potentially hazardous.'

Meanwhile, the US Federal Bureau of Investigation has been called in to remove the vials.