LONDON (Reuters) - Britain's best-selling author, Harry Potter creator J.K. Rowling, has donated 1 million pounds (S$2.09 million) to the campaign against Scottish independence, saying on Wednesday she believed Scotland was better off staying in the United Kingdom.

Rowling lives in the Scottish capital of Edinburgh and will be among about four million voters to decide at a Sept 18 referendum whether Scotland should end its 307-year tie to England.

Rowling said she was concerned about the potential economic impact of Scotland going it alone. "The more I have read from a variety of independent and unbiased sources, the more I have come to the conclusion that while independence might give us opportunities - any change brings opportunities - it also carries serious risks," Rowling wrote in a statement on her website.

A spokesman for the pro-union Better Together campaign confirmed Rowling had donated 1 million pounds to the campaign.