British author JK Rowling will publish new Harry Potter material every day from December 12 to 23 on her website Pottermore.com as a gift to fans.
The author made the announcement on Facebook, saying the stories will be available each day from 1pm GMT for fans who solve an online riddle.
The new material will include "shiny gold Galleons and even a new potion or two", the author said, and the riddles will be written in rhyme.
• Read more: JK Rowling to release Harry Potter stories for Christmas
Harry Potter has been one of the greatest ever publishing successes, with more than 450 million copies sold around the world and the films raking in $7.57 billion at the box office.
