Hillary Clinton said she would not rule out questioning the legitimacy of last year's US election if further Russian interference is uncovered.

However, the defeated Democratic nominee admitted there is no way for her to challenge the results now.

Mrs Clinton has re-emerged into the spotlight to promote her new book, What Happened, about the 2016 election, in which she calls Mr Trump "a clear and present danger to the country and the world."

In the book, the former secretary of state assigns blame for her presidential loss on several factors, including interference from Russian hackers, accusations levelled at her by former FBI Director James Comey and even her gender.

Asked in an NPR interview whether she would "completely rule out questioning the legitimacy of this election if we learn that the Russian interference in the election is even deeper than we know now?", Mrs Clinton replied: "No. I would not ... I wouldn't rule it out."