The team behind much-hyped erotic romance Fifty Shades of Grey has confirmed that two sequels are already in the works, according to fans attending a special screening of the upcoming film.

The news was reportedly announced on Friday by director Sam Taylor-Johnson, EL James, who wrote the original novel, and stars Jamie Dornan and Dakota Johnson at New York’s Zeigfeld Theatre. Fans began tweeting the news immediately, though studio Universal said there was no official confirmation.

Taylor-Johnson also told the US Today show on Saturday morning that she was signed up for the first sequel, Fifty Shades Darker. There are unconfirmed suggestions on Twitter that the new movie will begin shooting as early as June for a release in February next year.

James has written two further books in the Fifty Shades series. Fifty Shades Darker, which charts the deepening relationship between kinky billionaire Christian Grey and his well-remunerated sex slave Anastasia Steele, was published in 2011. Fifty Shades Freed, which follows the pair as they embark on married life, arrived on bookshelves in 2012. The trilogy has sold more than 100m copies worldwide, with the books translated into more than 50 languages.

Taylor-Johnson’s film, which stars Dornan and Johnson as Grey and Steele, is being released in time for Valentine’s Day on both sides of the Atlantic. Observers expect it to be one of 2015’s biggest movies, with a predicted opening of more than $60m in the US alone. Advanced ticketing site Fandango reports the film is the fastest-selling movie to have secured a US R-rating in its 15-year history.