Los Angeles (AFP) - Avengers superhero actors Jeremy Renner and Chris Evans apologised Thursday for calling co-star Scarlett Johansson's character in the blockbuster movie a "slut", saying it was just a tasteless joke.

Renner, who reprises his role as Hawkeye in the sequel Avengers: Age Of Ultron, made the offending comments in a television interview alongside fellow superhero star Evans, who plays Captain America.

An interviewer asked them what they thought about Johansson's character, Black Widow, opting not to get together romantically with either of them.

"She's a slut!" Renner told the Digital Spy interviewer, triggering huge guffaws from Evans, who added: "I was going to say something along that line... a complete whore."

Social media went ballistic, and on Thursday Renner's publicist issued an apology on his behalf, saying the actor was simply exhausted from the slog of promoting the new movie.

"I am sorry that this tasteless joke about a fictional character offended anyone. It was not meant to be serious in any way. Just poking fun during an exhausting and tedious press tour," he said.

Evans' representatives did not immediately respond to a request for comment, but in a statement to Entertainment Weekly he said: "We answered in a very juvenile and offensive way that rightfully angered some fans. I regret it and sincerely apologise."

The original 2012 The Avengers became the third-highest grossing movie in cinema history, taking more than US$1.5 billion (S$2 billion) at the box office, only beaten by Avatar (2009) and Titanic (1997).