The 45-year-old actor, who has had several projects financed by the film producer, said he is horrified to learn of his alleged conduct, while calling for more women in positions of power.
Ben Affleck has broken his silence on Harvey Weinstein.
The 45-year-old actor took to Facebook and Twitter on Tuesday to condemn the film producer following newly published allegations by multiple women claiming Weinstein sexually assaulted them.
"I am saddened and angry that a man who I worked with used his position of power to intimidate, sexually harass and manipulate many women over decades," Affleck wrote. "The additional allegations of assault that I read this morning made me sick."
Affleck went on to call for an industry-wide change with regard to supporting women who come forward, and getting more females in executive roles.
"This is completely unacceptable, and I find myself asking what I can do to make sure this doesn’t happen to others," he wrote. "We need to do better at protecting our sisters, friends, co-workers and daughters. We must support those who come forward, condemn this type of behavior when we see it and help ensure there are more women in positions of power."
Several films that Affleck has appeared in were financed by Miramax -- co-founded by Weinstein -- early in his career, such as 1997's Good Will Hunting, 1998's Shakespeare in Love and a number of director Kevin Smith's movies.
However, Affleck's Phantoms co-star -- another Miramax picture -- took issue with his statement on Twitter, accusing the actor of being aware of at least some of Weinstein's alleged misconduct.
"Ben Affleck f**k off," the 44-year-old actress tweeted. "'GODDAMNIT! I TOLD HIM TO STOP DOING THAT.' You said that to my face. The press conf I was made to go to after assault. You lie."
ET has reached out to Affleck's rep.
After learning of the allegations, Smith himself took to Twitter to express shame for having worked with Weinstein, writing, "He financed the first 14 years of my career - and now I know while I was profiting, others were in terrible pain. It makes me feel ashamed."
While Weinstein, who has been fired by the Weinstein Company, apologized in a letter to The New York Times for past behavior that "has caused a lot of pain," he has denied through his lawyer and rep many of the allegations levied against him.
Weinstein's lawyer, Charles J. Harder, said in a statement to ET that the initial Times story last week was "saturated with false and defamatory statements." And, after the explosive article in The New Yorker published on Tuesday, which includes allegations made by actresses Mira Sorvino, Rosanna Arquette, Asia Argento and others, Weinsten's spokesperson, Sallie Hofmeister, issued a statement denying any allegations of non-consensual sex and retaliation.
“Any allegations of non-consensual sex are unequivocally denied by Mr. Weinstein. Mr. Weinstein has further confirmed that there were never any acts of retaliation against any women for refusing his advances," the statement reads. "Mr. Weinstein obviously can’t speak to anonymous allegations, but with respect to any women who have made allegations on the record, Mr. Weinstein believes that all of these relationships were consensual. Mr. Weinstein has begun counseling, has listened to the community and is pursuing a better path. Mr. Weinstein is hoping that, if he makes enough progress, he will be given a second chance.”
Watch the video below for more on the sexual harassment claims made about Weinstein.