The Thorn Birds, an Australian saga of forbidden passion that became a TV mini-series, has been turned into a musical.

Author Colleen McCullough says the stage version of her book, directed by Michael Bogdanov, is slated to tour Britain this spring.

"There are certain iconic moments in television history that mean something to people and The Thorn Birds was one of these," Bogdanov told the Observer newspaper.

The book, published in 1977, was a sensation — chronicling a decades-long affair between a Roman Catholic priest and a woman on a sheep station in the outback.

It became the second-highest rated mini-series on U.S. television — Roots holding the No. 1 place — when it premiered in 1983 with Richard Chamberlain and Rachel Ward in the title roles. The nine-part series was directed by Vancouver's Daryl Duke.

The novel has sold more than 30 million copies since its first outing.

McCullough, now 71, wrote the first draft of her novel in just three months outside of her day job as a neurophysicist at Yale University.

The book's massive international success prompted the reclusive writer to move to remote Norfolk Island in the Pacific.

'I could not put it down'

Since then, McCullough has ventured into other types of writing, including a seven-volume series on the history of Rome.

She did not give her bestseller a second thought until she was contacted by Gloria Bruni, a German composer and opera star, some 25 years after the book's publication. Bruni sent her some of the songs she had written, inspired by the story.

The two collaborated on writing the musical but decided to hire Bogdanov to make it better.

The director — whose credits include acclaimed productions with the Royal Shakespeare Company and the Royal National Theatre in Britain — admits he hadn't read the book before but picked up a copy after he was contacted to direct the musical.

"I found, like most people, I could not put it down. As soon as I landed in America I contacted them and said I wanted to work on the musical with them."

Costumes for the cast of 18 have been designed by David Emmanuel, who helped create the wedding dress for the late Diana, Princess of Wales.