Actor Mark Wahlberg has agreed to donate the $1.5 million ($1.9m) he earned for All the Money in the World reshoots to the Time's Up initiative after reports co-star Michelle Williams made less than $1,000 ($1,265) for the retakes.

Wahlberg said he would donate the money to the sexual misconduct defence initiative in the name of his co-star Williams.

"I 100 per cent support the fight for fair pay," he said in a statement.

Williams issued a statement, saying: "Today isn't about me. My fellow actresses stood by me and stood up for me, my activist friends taught me to use my voice, and the most powerful men in charge, they listened and they acted."

She noted that "it takes equal effort and sacrifice" to make a film.

"Today is one of the most indelible days of my life because of Mark Wahlberg, WME (William Morris Endeavor) and a community of women and men who share in this accomplishment."

Agency William Morris Endeavor, which represents both Wahlberg and Williams, donated a further $500,000 to #Time'sUp, the legal defence fund founded in response to the #MeToo movement.

William Morris Endeavor said in a statement that wage disparity conversations should continue and "we are committed to being part of the solution".

The donations came after directors and stars, including Jessica Chastain and Judd Apatow, shared their shock at reports of the huge pay disparity for the Ridley Scott film.

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The 10 days of reshoots were necessary after Kevin Spacey was replaced by Christopher Plummer when accusations of sexual misconduct surfaced against Spacey.

The American Broadcasting Company reported that last December that Williams told the broadcaster she was in favour of the reshoots because she did not want the film to be tainted by the Spacey scandal, and declined an additional salary.

USA Today also said that in December, Scott told the newspaper that "everyone did it [the reshoots] for nothing".

But on Tuesday, USA Today wrote that Wahlberg's team negotiated his $1.5 million fee, but Williams was not told about it.

Williams and Plummer were nominated for Golden Globes for their performances.

Kevin Spacey in a scene from All The Money In The World, before he was cut from the film. ( Supplied: Sony Pictures )

ABC/AP