Robert Downey Jr has lent his voice to calls for a solo Black Widow movie.

Over the last few months, there have been an increasing number of prominent players in the movie industry who have urged Marvel Studios to grant a standalone film for Black Widow, played by Scarlett Johansson - and Downey Jr has become the latest and, perhaps, most influential voice to do so.

Reflecting on the issue, Downey Jr told USA Today newspaper: ''I think that the interesting thing particularly after Guardians with Zoe [Saldana, or] even from the first 'Iron Man' where Pepper was kind of this really - to me the 'Iron Man' franchise would never have taken off without [Gwyneth] Paltrow.

''There's something about her that grounded the story. She's not your typical lady in a superhero movie, and then by Iron Man 3 she's swallowing serums and putting on suits and kicking [butt] and all that stuff.

''But it would be kind of more appropriate for a character that already was like a Black Widow [to lead a movie]. It just seems like whatever Scarlett does, people want to go see it.''