Harry Potter star Emma Watson admitted that she was completely upset after a website threatened to post nude photos of her.

Last September, a web page entitled Emma You Are Next, featuring an image of the 24-year-old actress next to a countdown, appeared to have been created by a user of 4Chan. The page carries the threat: "Never forget, the biggest to come thus far."

Watson, who is UN Women Goodwill Ambassador, was speaking at Facebook's headquarters in London to mark International Women's Day, and explained how the website targeted her after she spoke out for women's rights.

"After I gave my speech [at the UN] there was a website threatening to release naked pictures of me," she said.

"I knew it was a hoax, I knew the pictures didn't exist, but I think a lot of people that were close to me knew gender equality was an issue but didn't think it was that urgent, that it was a thing of the past," Watson said.

"And then when they saw that the minute I stood up talking about women's rights I was immediately threatened, I think they were really shocked, my brother was particularly upset.

"This is a real thing that's happening now, women are receiving threats.

"I was raging, it made me so angry, I was like, this is why I have to be doing this. If anything, if they were trying to put me off it, it did the opposite," she added.