LONDON — J.K. Rowling, the world’s richest author, was added as a defendant in a lawsuit against her publishers alleging that she copied part of a children’s book in writing “Harry Potter and The Goblet of Fire.”

The lawsuit, filed by the estate of the English children’s author Adrian Jacobs, alleges that part of his 1987 book “The Adventures of Willy the Wizard: No. 1 Livid Land” was copied by Rowling. A year of wizard contests in the book was similar to a central theme of “The Goblet of Fire,” the lawsuit says, according to a statement issued Wednesday by the estate.

Jacobs’ estate sued Bloomsbury Publishing in a London court in June, according to the statement. The suit claims that Jacobs used concepts and themes such as wizard prisons, wizard hospitals and wizard colleges before Rowling did. The two authors also shared an agent, Christopher Little, who manages the Harry Potter brand worldwide, according to the statement.

Rowling was added to the suit under her married name, Joanne Kathleen Murray, “after discovering legal cause of action against her within the last six years,” the estate said.

— From wire reports