Harry Potter creator J.K. Rowling accused British Prime Minister David Cameron on Saturday of betraying victims of press intrusion after he opposed calls by a major inquiry for laws to regulate newspapers.

Rowling, who told the Leveson Inquiry last year that journalists had repeatedly invaded her children's privacy, said Cameron had let down people like her who had decided to testify about press misconduct.

"I am alarmed and dismayed that the prime minister appears to be backing away from assurances he made at the outset of the Leveson inquiry," the author said in a statement on the website of Hacked Off, a group for victims of press intrusion.

"Having taken David Cameron?s assurances in good faith at the outset of the inquiry he set up, I am merely one among many who feel duped and angry in its wake," the multimillionaire writer added.

Senior judge Brian Leveson said in his long-awaited 2,000-page report released on Thursday that there should be a new independent self-regulatory body for the British press that is underpinned by new legislation.

Cameron immediately warned that new laws could threaten press freedom -- setting up a clash with the Liberal Democrat deputy prime minister of his coalition government, Nick Clegg, and with the opposition Labour party.

Rowling said: "Mr Cameron said that he would implement sensible recommendations: it is time for him to honour that commitment and join the other political leaders by supporting the Leveson recommendations in their entirety."

The author, whose adult novel "The Casual Vacancy" received lukewarm reviews when it was released in September, was one of the most outspoken critics of the British press when she testified to the inquiry in November 2011.

She said one journalist slipped a letter into her daughter's schoolbag while another contacted a headmaster over untrue claims that her daughter upset friends by telling them that boy wizard Harry Potter died in the last book in the series.

Cameron set up the inquiry over allegations of phone-hacking at Rupert Murdoch's now-closed News of the World tabloid, and it heard from nearly 500 witnesses including celebrities, crime victims, media figures and politicians.

Hacked Off said 51,000 people had signed a petition calling on Cameron, Clegg and Miliband to work together to implement the findings of the Leveson report in full.