Film director Oliver Stone has praised US intelligence leaker Edward Snowden as a "hero".

Speaking at a news conference in Tokyo, the 66-year-old said: "Edward Snowden is a hero. Because he did this not for profit, not to give, exchange, give secrets away that could hurt our country supposedly...He is doing it out of conscience."

Stone was in Japan to promote his new ten-part documentary, The Untold History of the United States.

Edward Snowden has been granted asylum by Russia despite requests from the US that he be returned.