J.K. Rowling won four platinum awards, one for each of her best-selling Harry Potter novels.
The author didn't attend Friday's ceremony in London, but asked her publisher, Nigel Newton, to deliver a message of thanks.
"Despite what you may have read, and probably to Nigel's immense relief, I am happily incarcerated in a rather chilly Edinburgh, busily writing Book Five," Rowling's message said, referring to reports that she's suffering from writer's block.
The British book industry created the prizes, modeled after the music industry's gold and platinum records. The awards are based on sales in bookstores, in supermarkets and over the Internet.
Platinum awards recognize sales of more than 1 million books; writers who have sold more than 500,000 copies receive gold awards. Rowling is believed to have sold more than 100 million books worldwide.
Other authors who received platinum awards: Louis de Bernieres for "Captain Corelli's Mandolin," Helen Fielding for "Bridget Jones's Diary" and Frank McCourt for "Angela's Ashes."