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Ten thousand copies of a "mummy porn" novel - based on Twilight characters and targeted at housewives - have hit New Zealand bookshelves.

Fifty Shades of Grey by British author E.L. James went on sale in New Zealand bookstores this week to rapid sales. It has been dubbed "mummy porn" for its popularity among mothers when it first gained popularity in electronic form.

The book is a tale of sex between a 21-year-old woman and a mysterious billionaire with an inclination toward bondage.

Overseas, it is said to be behind an exponential growth in the popularity of erotic fiction.


Avon publisher Caroline Ridding said there was a phenomenal boom in erotica sales driven almost exclusively by female readers.

At Whitcoulls in Queen St, Fifty Shades of Grey is unassumingly displayed between crime thrillers on a central table.

It does not have the prominence of The Hunger Games, but neither is it hidden away.

It features a dark blue background with a silver tie - apparently one of the instruments used in the book's scenes of bondage.

Reviewers have compared the book to The Da Vinci Code - an amateurish page-turner - but with sex scenes that make you cringe.

The book first appeared on a fan fiction site using the main characters from Twilight.

The characters' names and circumstances were changed to avoid copyright infringements when it was published as an e-book, which became a sensation in the United States, topping the New York Times bestseller list.

E-books, read on tablets and other portable devices, are said to be part of the reason behind erotica's recent rise. They do not show a book's cover, letting readers flick through steamy literature in public without passersby noticing.

But Fifty Shades of Grey 's popularity appears to be holding up even in print form.

After just two days of sales in New Zealand, it reached number 6 on our international bestseller list.

Ten thousand sales are expected in three to four weeks, which would put it at the top of the list, said publisher Random House NZ.