LOS ANGELES • Warner Bros is not enchanted with fans who organise Harry Potter-themed events.

It fears that such outings damage the brand value of its movie franchise and has sent letters demanding a stop to unauthorised festivals.

But, according to the Evening Standard, the move has riled organisers, which feel their activities actually ramp up brand recognition.

Still, Warner Bros is telling the folk behind a Quidditch sport tournament in Philadelphia not to field any names, places or objects from the J.K. Rowling book series.

"Warner Bros is always pleased to learn of the enthusiasm of Harry Potter fans, but we are concerned, and do object, when fan gatherings become a vehicle for unauthorised commercial activity," it said.

Fans are seeking support and even implored Rowling to intervene. But the author, who will be inducted into Seattle's Museum of Pop Culture's Science Fiction and Fantasy Hall of Fame later this year, is staying neutral for now.