The woman, identified as Effie, spoke out on Thursday during a press conference with her attorney Gloria Allred.
In a statement to The Independent, Hammer’s attorney Andrew Brettler said that Effie’s “own correspondence with Mr Hammer undermines and refutes her outrageous allegations”.
The allegation comes after the actor’s name was trending on Twitter earlier this year after direct messages allegedly sent by him surfaced, alluding to misconduct.
The messages, which appeared to be sent from the actor's official Instagram account, describe graphic sexual fantasies, and included references to rape, violence and cannibalism.
Amid the scandal, Hammer stepped back from his upcoming romantic comedy Shotgun, which also stars Jennifer Lopez.
Hammer dismissed the claims, which he referred to as "bulls**t".
In a statement at the time, the Call Me By Your Name star said: "In light of the vicious and spurious online attacks against me, cannot in good conscience now leave my children for four months to shoot a film in the Dominican Republic. Lionsgate is supporting me in this and I’m grateful to them for that”.
Following the alleged leak, past interviews with the star have resurfaced, in which he discusses rough sex and his sex life with his wife, Elizabeth Chambers, whom he separated from in July. Here's what the actor has discussed publicly about his sex life.
Hammer says he used to be a ‘dominant lover’
In an interview with Playboy in 2013, Hammer said he was previously "dominant lover" before getting together with his wife Elizabeth Chambers.
"I don't know how much we can put here without my parents being embarrassed, but I used to like to be a dominant lover," he said.
"I liked the grabbing of the neck and the hair and all that. But then you get married and your sexual appetites change. And I mean that for the better—it's not like I'm suffering in any way.
"But you can't really pull your wife's hair. It gets to a point where you say, 'I respect you too much to do these things that I kind of want to do.'"
Days later, the 34-year-old told E! Online that he had been drunk during the interview.
"Let's just say hindsight is 20/20," Hammer said. "Don't drink during an interview."
Hammer claims a woman tried to stab him during sex
Speaking to Elle magazine in 2013 while promoting his film The Lone Ranger, Hammer talked about his time on the LA party scene.
"I'd grown up in a household of so much love and so much good, everything just felt wholesome. Once I was on my own, I was like, Let's see how hot this candle can burn," he said.
Hammer said that for three or four years, he spent time partying, staying up for days and meeting girls he described as "bad, bad news".
"One chick tried to stab me when we were having sex. I should so not be telling this story," he said.
"She was like, 'True love leaves scars. You don't have any.' And then she tried to stab me with a butcher knife. Of course I promptly broke up with her... Seven months later."
Hammer is spotted liking BDSM tweets
The Rebecca actor liked a series of tweets in 2017 about ropes and bondage and didn't unlike them after this was reported on.
Later in 2017, BuzzFeed News published a scathing account of Hammer's career, describing him as a "little bit of an asshole". Hammer called the article "bitter AF" on Twitter, and deleted his account a day later.
The actor says Marquis de Sade would be his dream dinner guest
Whilst it was not a public comment on his sex life or his own preferences, in November last year, Hammer was asked which historical person he'd most like to have dinner with during an interview with Netflix Brazil, while promoting Rebecca.
The actor answered with Marquis de Sade, an 18th century philosopher who inspired the term sadist, offering no further comment on his choice.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies