New York: The United Nations closed its main dining room and staff cafeteria after "a suspicious envelope" was found, UN deputy spokeswoman Marie Okabe said.
She said on Thursday that the UN security staff called in New York City authorities to help investigate the contents of the envelope.
The envelope contained a white powder, a UN official said, speaking on condition of anonymity because the investigation is under way.
The former UN staff cafeteria, on the ground floor of the 39-storey Secretariat building overlooking New York`s East River, was recently renovated so that part of it is now the Delegates Dining Room.
All people in the dining facility were asked to leave, and many stood around outside waiting for word on whether they would be allowed to return and finish their lunches.