Lawyers for Rep. Katie Hill of California have threatened to sue the Daily Mail tabloid news site after it published nude pictures of her with a campaign aide.

A legal letter obtained by Politico accused the Mail of breaching California's law against distributing private explicit photos, known as revenge porn.

It also accused the Mail of defaming Hill by falsely saying she had a "Nazi-era" tattoo.

Hill on Wednesday said she'd had an "inappropriate" relationship with a campaign aide, who is also a subject of the Mail's story.

Separately, the House Ethics Committee said it was investigating claims that Hill had another relationship with a staffer. Hill denied there was a relationship.

Visit Business Insider's homepage for more stories.

Rep. Katie Hill is threatening to sue the Daily Mail tabloid news site after it published nude pictures of her with a campaign aide with whom she had a relationship.

Her attorneys accused the outlet, a sister publication of Britain's Daily Mail newspaper, of breaching revenge-porn laws in California that prohibit the unauthorized sharing of explicit photos.

Lawyers for Hill, who represents the 25th District of California, said the site also defamed her by claiming that she had a "Nazi-era" tattoo on her pelvic area.

A letter from the lawyers obtained by Politico said: "You have also exposed your publication to grave legal consequences for California has some of the strongest criminal laws in the United States against the secretive generation and distribution of private, sexual images.

"The California Penal Code accordingly makes it a criminal offense to 'intentionally distribute the image of the intimate body part or parts of another identifiable person.'"

It added that "the claim that Representative Hill has Nazi imagery on her body in the form of a tattoo is false and defamatory."

It demanded that the Mail take down the story immediately. As of Friday morning, the story was still on the Mail's website.

The outlet did not immediately respond to a request for comment from Business Insider on the threatened lawsuit.

Hill is the vice chair of the House Committee on Oversight and Reform, which is part of the impeachment investigation into President Donald Trump.

In a letter to constituents on Wednesday, Hill said she'd had an "inappropriate" relationship with a campaign aide.

"I know that even a consensual relationship with a subordinate is inappropriate, but I still allowed it to happen despite my better judgment," Hill wrote. "For that I apologize. I wish nothing but the best for her and hope everyone respects her privacy in this difficult time."

Last week, the conservative blog RedState published a nude picture of Hill brushing the hair of a person who it said was the aide.

The site said that it received the information from "multiple confidential sources" and that Hill and her estranged husband, Kenny Heslep, were in a polyamorous relationship with the woman. Further images were published by the Mail on Thursday, including one appearing to show the tattoo.

Separately, the House Ethics Committee said in a statement Wednesday that it was launching an inquiry into RedState's allegations that Hill violated ethics rules by having a relationship with another staffer, named by the blog as Graham Kelly, since her election to the House last year.

The committee noted that the investigation "does not itself indicate that any violation has occurred."

In her letter, Hill denied having a relationship with Kelly.

"Allegations that I have been involved in a relationship with Mr. Kelly are absolutely false," Hill said.

Kelly and Heslep did not immediately respond to Business Insider's requests for comment.

Hill wrote that she had alerted the Capitol Police to the publication of the intimate pictures by RedState.

"Distributing intimate photos with the intent to publish them is a crime, and the perpetrator should be punished to the full extent of the law," she wrote. "I have notified Capitol Police, who are investigating it, and therefore will have no further comment on the matter."

She said the source of the allegations and pictures was Heslep, whom she is divorcing and whom she described as abusive and "determined to try to humiliate me."