Robert Downey Jr could be set to reprise his superhero role in Iron Man 4 after the Avengers actor claimed Marvel and Disney have to "come to us" with a deal.

This is despite Downey Jr previously hinting that the role of Tony Stark in a fourth standalone film could be played by a younger actor.

Speaking to Entertainment Weekly, Downey Jr seemed to suggest nothing was set in stone, when he was asked about the possibility of reprising his role as the Marvel superhero in Iron Man 4.

"It's down to Kevin [Feige, Marvel Studios president] and Ike [Perlmutter, CEO of Marvel Entertainment] and Disney to come to us with what the proposal is and that's on us to agree or disagree," he said. "When things are going great, there's a lot of agreement.

"Right now, this has just been swell, hasn't it?" he continued, in reference to the upcoming Avengers: The Age of Ultron. "This has been a really good one and it feels good and we're having a good time.

"It's that thing of 'Why give up the belt when it feels like you can barely get jabbed?'" he apparently said, before adding: "Most people are saying that right when they get knocked out. The future is, as usual, uncertain."

Avengers stars Downey Jr, Chris Hemsworth and Scarlett Johansson are reportedly having heated discussions with Marvel over fees and renewal of contracts for sequels to their respective films.

Downey Jr was recently declared by Forbes to be the highest-paid actor in Hollywood. Marvel may need to pay him a lot of money to reprise his role in Iron Man 4.