Levinson: AP journalist explains background to story
13 December 2013 Last updated at 23:37 GMT
White House spokesman Jay Carney has said that Robert Levinson, the American citizen who disappeared from the Iranian island of Kish in 2007, was not a US government employee at the time.
The Associated Press has published a story alleging that Mr Levinson was working for the Central Intelligence Agency as a contractor on an unapproved mission when he went to Iran.
Ted Bridis, the AP's Washington Investigative Editor, explained the background to the story.