The latest instalment in the Harry Potter universe has recorded the highest first week of sales for a book since Nielson Bookscan began reporting on the New Zealand market.

Sales of Harry Potter and The Cursed Child Parts One and Two inNew Zealand reflect the phenomenal success of the book worldwide, with 3.3 million copies sold in North America, nearly 850,000 books in the UK, and more than 200,000 books in Australia sold during the first week.

‘Harry Potter and The Cursed Child Parts One and Two' has broken all sorts of records during its first week of sales. Photo: Hachette NZ/Facebook

But a Hachette NZ spokesperson says the publishing company is unable to disclose sales figures for New Zealand, because unlike the UK, US and Australia, not all Kiwi retailers contribute to Nielsen Bookscan.

However, the spokesperson adds the New Zealand figure is 'proportionally in line with the international sales”.

Harry Potter and the Cursed Child Parts One and Two is a play by Jack Thorne that's based on an original story by J.K. Rowling, Jack Thorne and John Tiffany. It opened at The Palace Theatre in London's West End on July 30 to critical acclaim.

The following day the Special Rehearsal Edition of the script was published containing the complete script, including stage directions, used by the original West End production during the play's preview period.

Hachette NZ sales and marketing director Melanee Winder says Harry Potter and the Cursed Child has made a lot of Kiwi readers very happy.

'We are continuing to work closely with local retailers to ensure this title stays at the top of the bestseller chart right through to Christmas and beyond.”

New Zealand stores have struggled to keep up with demand, with some reporting such strong pre-orders they sold through their initial order before the book even went on sale.