LOS ANGELES• Movie stars Emma Watson and Amanda Seyfried launched legal action on Wednesday after private pictures were stolen and posted online, while Mischa Barton spoke of her anguish over a leaked sex tape.
Although the photographs of 26-year-old Watson merely show her trying on outfits, the images of Seyfried and Barton show them in a series of compromising and sexually explicit poses.
Watson's publicist said the stolen pictures were taken during a fitting she had with a stylist "a couple of years ago".
He did not offer details about the circumstances of the shoot or how the images ended up in the wrong hands.
"They are not nude photographs. Lawyers have been instructed and we are not commenting further," he told Agence France-Presse.
Media reports said the pictures had been shared on the so-called "dark web" - an encrypted part of the Internet not easily accessible by users lacking specialist knowledge.
Watson stars in Disney's Beauty And The Beast, which is due to hit United States cinemas today.
Later on Wednesday, the legal team of Seyfried, 31, said it was pursuing a website that had posted nude photos of her, including images of "intimate moments" with her former boyfriend, celebrity gossip portal TMZ reported.
TMZ posted on its website what it described as a threatening letter from the actress' lawyer to the website Celeb Jihad, demanding it take down the images immediately.
Meanwhile, Barton, 31, told a news conference on the outskirts of Los Angeles that she was taking action to stop the potential sale of a sex tape made against her will in a so-called "revenge porn" case.
She said she had obtained a restraining order and that cease-and- desist letters had been sent to those believed to be trying to buy or sell the images. "I have been put through an incredibly hard and trying time," Barton, best known for her starring role on the Fox series, The O.C., said.
Reading from a prepared statement, she said her worst fears were realised when she learnt that someone she had loved and trusted had been filming her "most intimate and private moments" with hidden cameras.
"I came forward to fight this, not only for myself but for all the women out there," she said. "I want to protect them from the pain and humiliation that I have had to go through."
Her lawyer, Ms Lisa Bloom, said someone the actress had once dated was offering the tape for US$500,000 (S$700,000), adding that buyers could be prosecuted.
The images were recorded in the last year, she said, refusing to identify the culprit, citing an ongoing police investigation.
The theft comes amid a spate of cases in which female celebrities had private and potentially embarrassing images leaked online, sometimes with blackmail as the intent.
Last month, a 29-year-old Chicago man was jailed for nine months for hacking into the electronic accounts of celebrities - including actress Jennifer Lawrence - on Apple's iCloud service and stealing private information, including nude videos and photos.
Dozens of stars' photos were posted online during a phishing scheme in 2014, including shots of Rihanna, Kate Upton and Kirsten Dunst.
Apple admitted having been hit by a "targeted attack", but denied its cloud storage system had been breached.