Author J.K. Rowling has revealed she's already working on two new books, just days after her final Harry Potter book was released to the world.

"One is for children and the other is not for children,"was all she divulged in an interview with USA Today.

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J.K. Rowling, shown reading at the launch of Harry Potter and the Deathly Hallows at The Natural History Museum in London on July 20, says she doesn't feel capable of creating another 'fantasy universe.' She's writing two new books. ((Jamie Turner/Associated Press))

Rowling also said she doubts if she'll dip into the world of fantasy again.

"I think I've done my fantasy. To go and create another fantasy universe would feel wrong, and I don't know if I'm capable of it," said the 41-year-old.

Harry Potter and the Deathly Hallows sold more than 11 million copies in the U.K. and the U.S. on its first day of sales, July 21.The previous six books in the series about a teen wizard and his battle against evil forces have sold 325 million worldwide.

While she is working on two books simultaneously, Rowling said she will probably have to drop one of them.

"This is exactly the way I started writing Harry," she said. "I was writing two things… for a year before Harry took over."

In an interview with the Today Show recorded earlier this week, the author said finishing the series was "cathartic."

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A Harry Potter fan flips through the final book at a bookstore in New Delhi last Saturday. Rowling says she hopes the series will live on. ((Manish Swarup/Associated Press))

Rowling said she hopes fans of the series weren't influenced by all the spoilers.

"I wanted the reader to feel that anyone might die, as in life."

She also hopes the books will live on to delight other generations.

"Do I think they'll last? Honestly, yes."

Rowling has said she wentthrougha period of mourning after finishing Harry Potter and the Deathly Hallows, but as an author reputedly worth more than $1 billion US, she felt relieved.

"What's quite uplifting is that in the middle of all this sadness I feel about Harry ending— and I do feel a lot of sadness about it — is the thought that financially I don't have to publish immediately," she added.

"So I can take my time. And the idea of just wandering off to a cafe with a notebook, and writing and seeing where that takes me for a while is just bliss. Heaven. No pressure."