Image copyright AFP/Getty Image caption EL James was in New York to launch new novel Grey last week

EL James' new Fifty Shades of Grey spin-off novel has broken the first week UK sales record for adult books.

Grey sold 647,401 copies in its first three days, beating record holder Dan Brown's The Lost Symbol, which sold 551,000 copies in five days in 2009.

The book tells the same Fifty Shades story but from the perspective of male protagonist Christian Grey.

Despite being savaged by critics, it has become a hit in the US, selling more than 1.1 million in four days.

The figures take in paperback, audio and ebook editions.

"We've had magnificent support from across the trade," said Susan Sandon from publishers Cornerstone.

"The excitement and enthusiasm that Grey's publication has generated is totally irresistible and I am delighted with these early results."

James's Fifty Shades trilogy has been the publishing story of the decade, having now sold more than 125 million copies and spawning a record-breaking film starring Jamie Dornan and Dakota Johnson.

Image copyright Universal Pictures Image caption The Fifty Shades of Grey film broke box office records when it was released in February

The author announced new novel Grey on 1 June, crediting its existence to persistent fans who had begged her for more from Mr Grey and love interest Anastasia Steele.

It immediately topped book charts from pre-sale orders before being released last week.

Many reviews criticised the novel, including The Telegraph's Bryony Gordon who found the story "as sexy as a misery memoir" in her one-star review.

Author Jenny Colgan writing in The Guardian said - despite it being "rather fun" - it was "almost impossible to read Grey and not assume the narrator is going to end up in jail".

James' publishers also announced today the author will be taking part in a live Twitter Q&A in London on 29 June.