Nicole Kidman has said she needed permission from Kofi Annan to film inside the UN headquarters, for her latest movie, The Interpreter.

The actress explained that although re-creating the building as a film set and using computer generated images was an option, cast and crew-members worried that the movie would lose its impact.

Thankfully, Kofi Annan did allow the project to go ahead, and Kidman has revealed that she was required to prove her identity every time she accessed the building, despite filming for three months.

"It never changed over the three months that we filmed at the United Nations," she said. "There was no cutting corners. It would take five or ten minutes just to get through the gate and no matter how many times they saw you that day they'd check your identification."

Kidman plays a UN interpreter in the movie, which also stars Sean Penn.