Actor Blake Lively has accused her It Ends With Us director and co-star Justin Baldoni of sexual harassment on the set of the movie and a subsequent effort to "destroy" her reputation in a legal complaint.

The complaint obtained by The Associated Press, which The New York Times reported was filed on Friday with the California Civil Rights Department, precedes a lawsuit. 

It names Baldoni, the studio behind the film and Baldoni's publicists among the defendants.

In the complaint, Lively accuses Baldoni and the studio of embarking on a "multi-tiered plan" to damage her reputation following a meeting in which she and her husband Ryan Reynolds addressed "repeated sexual harassment and other disturbing behaviour" by Baldoni and a producer on the movie.

The plan, the complaint said, included a proposal to plant theories on online message boards, engineer a social media campaign and place news stories critical of Lively.

Lively claims Baldoni enlisted publicists and crisis managers in a "sophisticated, coordinated, and well-financed retaliation plan" meant to "bury" and "destroy" her if she publicly revealed her on-set concerns.

Here's a snippet of Lively's complaint:

"To safeguard against the risk of Ms Lively ever revealing the truth about Mr Baldoni, the BaldoniWayfarer team created, planted, amplified, and boosted content designed to eviscerate Ms Lively's credibility. 

"They engaged in the same techniques to bolster Mr Baldoni's credibility and suppress any negative content about him."

The complaint also says Baldoni "abruptly pivoted away from" the movie's marketing plan and "used domestic violence 'survivor content' to protect his public image".

Baldoni denies allegations

Baldoni's lawyer Bryan Freedman called the claims "completely false, outrageous and intentionally salacious".

He pushed back against Lively's allegations of a coordinated campaign.

Mr Freedman said the studio "proactively" hired a crisis manager "due to the multiple demands and threats made by Ms Lively during production".

Mr Freedman also said Lively threatened not to appear on set or promote the film "if her demands were not met".

What were Lively's demands?

The "demands" weren't detailed in Mr Freedman's statement.  

However, Lively's complaint listed 30 demands that she said Baldoni and others agreed to after their tense sit-down over her hostile work environment concerns.

This included:

• "no more showing of nude videos or images of women" to Lively and others on set 
• no more discussions about pornography, sexual experiences or genitalia
• Baldoni should not ask Lively's trainer about her weight without her consent
• Baldoni should not press Lively about her religious beliefs 
• Baldoni should make "no further mention of [Lively's] dead father"

An intimacy coordinator was also required to be on set whenever Lively shared a scene with Baldoni and he was barred from entering her trailer or the make-up trailer while she was undressed.

The demands also stipulated that there would be "no more improvising of kissing" scenes or adding of sex scenes to the film outside of the ones in the script Lively approved when she signed on.

"I hope that my legal action helps pull back the curtain on these sinister retaliatory tactics to harm people who speak up about misconduct and helps protect others who may be targeted," Lively said in a statement to the New York Times.

A representative for Lively referred the Associated Press (AP) to the Times report, in which Lively denied planting or spreading negative information about Baldoni or the studio.

Criticism over film's publicity campaign

It Ends With Us, an adaptation of Colleen Hoover's bestselling 2016 novel, was released in August, exceeding box office expectations with a $US50 million ($80 million) debut.

But the movie's release was shrouded by speculation over discord between the lead pair. 

Baldoni took a back seat in promoting the film while Lively took centre stage along with Reynolds, who was on the press circuit for Deadpool & Wolverine at the same time.

Baldoni — who starred in the telenovela send-up Jane the Virgin, directed Five Feet Apart and wrote Man Enough, a book pushing back against traditional notions of masculinity — did respond to concerns that the film romanticised domestic violence at the time. 

He told AP at the time that critics were "absolutely entitled to that opinion".

"If anybody has had that real-life experience, I can imagine how hard it would be to imagine their experience being in a romance novel," Baldoni said. 

"To them, I would just offer that we were very intentional in the making of this movie."

AP