LONDON - A British judge refused to dismiss a plagiarism lawsuit against "Harry Potter" author J.K. Rowling on Thursday, saying claims that the bestselling author stole ideas from an obscure fantasy book should be considered at a proper hearing.

Rowling and her publishers, Bloomsbury, had applied to court for the case to be immediately dismissed, saying the copyright infringement claims brought by the estate of the late author Adrian Jacobs had no real chance of succeeding.

But Justice David Kitchin ruled that the claims had a chance of success -- although he described this as being "improbable."

The lawsuit alleges that Rowling's book "Harry Potter and the Goblet of Fire" copied substantial parts of Jacobs' 1987 book, "The Adventures of Willy the Wizard -- No. 1 Livid Land." Jacobs' estate also claims that many other ideas and plot aspects from the 16-page volume were copied into the "Harry Potter" books. Jacobs died in London in 1997.

Rowling has called the claims unfounded and absurd, saying she only learned of the book in 2004. She has also said the idea for the "Harry Potter" series first came to her in 1990 during a train journey.

The seven Harry Potter books have sold more than 400 million copies and spawned a hit movie franchise and a theme park. Forbes magazine has ranked Rowling as one of the richest women in Britain, with an estimated wealth of $1 billion.

A one-day hearing will be scheduled to consider the case, Kitchin said. He ordered that Paul Allen, the trustee of Jacob's estate, pay money into court as security for the costs of the case.

A lawyer representing Allen said he was delighted that the case can go forward.

"If the claim does proceed, then J.K. Rowling and Bloomsbury will be required to explain how the similarities between the two works came about, when to date there has been a refusal to disclose key manuscripts and notebooks," said Allen's lawyer Nick Kounoupias.

Rowling has hinted that she may yet write another novel in her popular series. In a recent interview with Oprah Winfrey, she said the characters are still in her head and she "could definitely" write several new books about them.