Harry Potter author JK Rowling has branded claims that she copied ideas from a fellow author "absurd" and "unfounded".

The author reacted angrily to the plagiarism claims after the estate of the late author Adrian Jacobs filed a lawsuit against Rowling's publisher Bloomsbury last year, claiming that the multibillion-pound series stole ideas from Jacobs' 'Willy the Wizard' stories.

Rowling, who has faced similar claims about the Harry Potter series over the years, said: "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."

Paul Allen, the estate's trustee, said he would be seeking legal advice over whether subsequent film and theme park franchises could be included under copyright law in what could turn out to be a "billion-dollar case", according to his agent, Max Markson.

The lawsuit related to Jacobs' book The Adventures Of Willy the Wizard No 1: Livid Land, portions of which are alleged to have been used for Rowling's fourth book, Harry Potter and the Goblet of Fire.

Bloomsbury said they could not find any evidence that work had been lifted from Jacobs' stories.

Copyright © Press Association 2010