JK Rowling's Potter books have sold more than 400 million copies
Harry Potter author JK Rowling has said she plans to ask a court to dismiss accusations that she plagiarised parts of the best-selling book series.
Legal action accusing her of stealing ideas about the wizard from another British author was filed on Wednesday.
The estate of late author Adrian Jacobs, who died in 1997, are suing Rowling and Bloomsbury Publishing PLC.
Ms Rowling - whose books have gained worldwide recognition - called the claims "absurd" and "unfounded".
The writer said: "I am saddened that yet another claim has been made that I have taken material from another source to write Harry.
"The fact is I had never heard of the author or the book before the first accusation by those connected to the author's estate in 2004; I have certainly never read the book.
"The claims that are made are not only unfounded but absurd and I am disappointed that I, and my UK publisher Bloomsbury, are put in a position to have to defend ourselves.
"We will be applying to the Court immediately for a ruling that the claim is without merit and should therefore be dismissed without delay."
Mr Jacob's estate has alleged that substantial parts of The Adventures of Willy the Wizard - No 1 Livid Land can be found in the fourth book in Rowling's best-selling series, Harry Potter and the Goblet of Fire.
Max Markson, who represents Paul Allen, the trustee of Mr Jacob's estate, said: "I estimate it's a billion-dollar case. That'll be the decision of the courts, obviously."
Last year Bloomsbury denied the allegations, which were first made in 2004, calling them "unfounded and untrue".
Bloomsbury has always maintained it had been unable to identify any text in the Potter books which had apparently been copied.