The hotly-anticipated new Harry Potter novel may not be published until 2003, disappointing thousands of fans waiting for the latest adventure of the young wizard.

Harry Potter and the Order of the Phoenix, the fifth in the series, was widely expected to be in bookshops in 2002 - as the previous books had been delivered on a yearly basis from 1997 to 2000.

There was no new book in 2001 but there was the blockbuster film, Harry Potter and the Philosophers' Stone.

Potter fans have become used to their yearly treat

But a spokeswoman for JK Rowling told BBC News Online that there had been no deadline set for publication of the new Potter adventure.

"It could be this year, it could be next.

"There has never been a publication date set, nor has a deadline been broken.

"Because the first four books were published in consecutive years, people just assumed that the next would be this year."

The spokeswoman also quashed speculation that the novel might be longer than previous Potter stories.

Manuscript

"We have absolutely no idea of the length," she said.

A spokeswoman for Rowling's publishers Bloomsbury said: "She is happily writing Harry Potter and the Order of the Phoenix and as soon as we have the completed manuscript we will announce a publication date."

The publishing house admitted it has "no idea" about the length of the book: "All her books are different."

A statement on the Bloomsbury website, however, said that "in a perfect world the date would be early autumn 2002".

Rowling has promised to write seven Potter books in all - one for each year Harry spends at Hogwart's School.

Potter mania in the UK is likely to receive another boost with the impending release of video of the Harry Potter film - which some observers predict may outsell Titanic, the biggest seller to date.

HMV will be opening stores at midnight on Friday to meet the likely demand, with Asda also promising to open 58 supermarkets.

Online retailer Amazon has also reported taking a record 36,000 pre-orders in the UK alone.