Robert Downey Jr walks out of Channel 4 interview

Downey Jr was in London to promote Avengers: Age of Ultron

Robert Downey Jr has been seen walking out of an interview with Channel 4 News when asked about his past problems with drugs.

Krishnan Guru-Murthy was interviewing him about his new film, Avengers: Age of Ultron, when things turned awkward.

Asked about his past drug problems and his time spent in prison, the US actor abruptly ended the interview.

"It's getting a bit Diane Sawyer and you're a bit of a schmuck," he was heard saying while exiting.

US broadcaster Sawyer is renowned for her probing personal questions and the confessional nature of the interviews she conducts with celebrities.

At the start of the interview, broadcast on Wednesday, Downey seemed happy to answer questions about the new Avengers movie and his role as Iron Man.

But the mood turned when he was asked about a quote he gave to the New York Times some years ago, in which he had made reference to his time in prison.

The actor declined to expand on the quote, saying it had come at a specific time.

Guru-Murthy went on to bring up Downey Jr's relationship with his father and "the dark periods you went to," prompting the actor to say: "I'm sorry, what are we doing?"

A publicist off camera then stopped the interview, at which point Downey Jr jumped up and left the room.

Guru-Murthy tweeted the news about the walk out

It is not the first time a Hollywood personality has been unhappy with Guru-Murthy's line of questioning.

In 2013 Quentin Tarantino refused to discuss the violence in his film Django Unchained, telling him: "I'm shutting your butt down."