The film adaptation of best-selling erotic novel "Fifty Shades of Grey" has been pushed back to 2015, studio Universal Pictures said on Wednesday.

The film was originally set to be released on August 1, 2014, but is now scheduled to be in cinemas on February 13, 2015, in time for Valentine's Day.

Universal did not give a reason for postponing the film's release date, but casting lead character Christian Grey was tripped up when "Sons of Anarchy" star Charlie Hunnam pulled out of the role on October 13, six weeks after being cast.

Northern Irish actor and former Calvin Klein fashion model Jamie Dornan, 31, signed on to replace Hunnam on October 24. Dornan will star alongside American actress Dakota Johnson in the film directed by Sam Taylor-Wood.

"Fifty Shades of Grey," about a passionate relationship between literature student Anastasia and the wealthy and mysterious entrepreneur, Grey, was written by British author E.L. James and published in 2011. It became a cultural phenomenon, spawning offshoots and parodies.

The film is expected to start shooting early next month. It will be distributed by Universal Pictures' Focus Features.

Described as "mummy porn" by critics, James' debut novel, the first in the "Fifty Shades" trilogy, became Britain's fastest paperback to reach 1 million sales.