Fifty Shades of Grey trilogy sells 100m copies

Series has sold over 27m copies in the UK and Commonwealth countries

EL James' bestselling series has sold 100m copies (Getty Images)

The erotic trilogy Fifty Shades of Grey has become one of the biggest-selling book series of all time, having sold 100 million copies worldwide.

The EL James series, which has been dubbed "mummy porn", has sold 27 million copies in the UK and Commonwealth countries, with moe than one million copies sold in Germany, France, Spain, Brazil and The Netherlands.

The series has sold more than 45 million copies in the US since its publication in June 2011, making it the fastest-selling book series in publisher Random House’s history.

At the peak of its popularity, two copies of Fifty Shades of Grey were sold every two seconds.

The sales figures put the mummy porn trilogy on a similar level to Ian Fleming’s James Bond series, which was first released in 1953.

The erotic romance is still to catch vampire novel Twilight and CS Lewis’ classic series The Chronicles of Narnia, which have each sold 120 million copies worldwide.

But EL James’ novels still have a long way to go until they beats JK Rowling’s hit series, which has sold 450 million copies since Harry Potter and the Philosopher’s Stone was first published in 1997.

A Fifty Shades of Grey film is due to be released in 2015 with artist and director Sam Taylor-Johnson at the helm.

The film was due to debut in 2014 but has been pushed back to St Valentine’s Day 2015 because of casting problems with the lead character, Christian Grey.

British actor Charlie Hunnam left the production last year, citing a busy schedule and family commitments, and has now been replaced by "The Fall" star Jamie Dornan.

Dakota Johnson will play Anastasia Steele, a college student who becomes infatuated with Christian Grey who introduces her to the world of S&M.

With additional reporting from the Press Association