Google is to be sued for $15 million (£9 million) by an anonymous blogger who was unmasked by the internet search company.

Rosemary Port said that Google had failed to protect her right to privacy when the company obeyed a court order to reveal her name after she used her blog to accuse a former Vogue model of being a "psychotic, lying, whoring ... skank".

Liskula Cohen, 36, won a landmark case in a New York court last week, forcing Google to disclose the online identity of Ms Port, 29, a Fashion Institute of Technology student, who created her "Skanks in NYC" blog a year ago using Google's Blogger.com program.

Legal experts said that the ruling stripped away some of the anonymity provided by the web, making people who post offensive blogs, videos or tweets more responsible for their anonymous statements.

In the UK, bloggers who operate behind the cloak of anonymity have no right to keep their identities secret, the High Court ruled in June. In a landmark decision, Mr Justice Eady refused to grant an order to protect the anonymity of a police officer who was the author of the NightJack blog.

He ruled that Richard Horton had no “reasonable expectation” to anonymity because “blogging is essentially a public rather than a private activity”.

Ms Cohen claimed that Ms Port had anonymously posted photographs and “defamatory statements concerning her appearance, hygiene and sexual conduct that are malicious and untrue".

The New York Supreme Court ruled that Google must reveal the identity of the blogger.

Judge Joan Madden rejected Ms Port's claim that the blogs were a "modern-day forum for conveying personal opinions, including invective and ranting" and should not be treated as factual assertions.

After the court ruling Google turned over the e-mail address and IP addresses from each time the blogger had logged on to the blog, allowing Ms Cohen to discover the identity of her tormentor.

She said she was relieved to discover that the woman who created the blog was not someone close to her and decided not to continue with a defamation suit. The blog was deleted in March.

Google said that users of Blogger.com agree to a privacy policy that allows the company to share personal information if required by legal action.

"We sympathise with anyone who may be the victim of cyber bullying," Andrew Pederson, a Google spokesman, said.

"We also take great care to respect privacy concerns and will only provide information about a user in response to a subpoena or other court order.

"If content is found by a court to be defamatory, we will, of course, remove it immediately."

Ms Port told the New York Daily News that the model should blame herself for all the publicity.

"This has become a public spectacle and a circus that is not my doing. By going to the press, she defamed herself," Ms Port said.

She added that she would sue Google for failing to protect the rights of its users. Her attorney, Salvatore Strazzullo, said that Google would be charged with breaching "its fiduciary duty to protect her expectation of anonymity".

"I feel proud to live in a country where you're not persecuted for your opinions," Ms Port said. "That right has to be protected.

"Even though people are now taking shots at me on the web, I believe those people have a right to their opinions — and their anonymity," she told the Daily News.

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