JK Rowling has indicated that she intends to vote against Scottish independence in the 2014 referendum, saying: "I'm pro-union."

Her comment comes in a wide-ranging interview today to promote her new novel, The Casual Vacancy, her first adult book since the Harry Potter series, which is published on Thursday.

The Guardian interviewer writes of Rowling: "She is not so private that she won't say which way she'll vote in the Scottish referendum – 'I'm pro union."

It is thought to be the first time that the Edinburgh-based author has made such a declaration, although she is a known friend of Sarah and Gordon Brown, and made a £1m donation to the UK Labour party in 2008.

Leaders of the Better Together campaign are expected to welcome today's comment, however brief, given that the pro-independence campaign have paraded an array of Scottish celebrities to back their cause.