NEW YORK (Reuters) - British author J.K. Rowling has outed one of the main characters of her best-selling Harry Potter series, telling fans in New York that the wizard Albus Dumbledore, head of Hogwarts school, is gay.

Speaking at Carnegie Hall on Friday night in her first U.S. tour in seven years, Rowling confirmed what some fans had always suspected -- that she "always thought Dumbledore was gay", reported entertainment Web site E! Online.

Rowling said Dumbledore fell in love with the charming wizard Gellert Grindelwald but when Grindelwald turned out to be more interested in the dark arts than good, Dumbledore was "terribly let down" and went on to destroy his rival.

That love, she said, was Dumbledore's "great tragedy".

"Falling in love can blind us to an extent," she said.

The audience reportedly fell silent after the admission -- then erupted into applause.

Rowling, 42, said if she had known that would be the response, she would have revealed her thoughts on Dumbledore earlier.

Fans on the top Potter fan site TheLeakyCauldron.org (http://www.the-leaky-cauldron.org) were divided on the news, some uncertain Rowling wasn't going to backtrack on the announcement, others saying it was unnecessary, and some welcoming the extra information on Dumbledore.

"This is even more awesome because it adds another layer to Dumbledore's character, which is already so rich and complicated. I hope he got over Grindlevald (sic) and fell in love again," wrote Amanda.

Rowling said she had read through a script for the movie adaptation of the sixth book in the series, "Harry Potter and the Half-Blood Prince" and corrected a passage in which Dumbledore was reminiscing about past loves by crossing it out and scrawling "Dumbledore is gay" over it.

Rowling, a mother of three, is now estimated to be worth $1.12 billion, making her the first dollar-billionaire author.

"Harry Potter and the Deathly Hallows" -- the seventh and final book in the boy wizard series -- became the fastest-selling book in history when it was released in July.

More than 11 million copies were sold in the first 24 hours in the United States and Britain.