Brett Haley has teased that the 'Grease' prequel 'Summer Loving' will be a ''full-on'' musical.

The 'Hearts Beat Loud' filmmaker is attached to direct the flick, a prequel to the classic 1978 movie starring John Travolta and Olivia Newton-John, and has promised that it will remain true to the original film.

Speaking to CinemaBlend, Brett said: ''I can't say much about it, but I can tell you, yeah it's going to be a full-on 'Grease' musical.

''I can tell fans of the franchise it's going to be really true to the movie and I also tell people who maybe don't like musicals that I think it'll be something that will be a wonderful experience and a wonderful, surprising, fun, feel-good, fully-realised journey.''

Haley added: ''So I'm really excited about what we're cooking up, and it's a dream project for me. I feel really honoured to have gotten it.''

It was confirmed last month that Brett would be helming the film, which gets its name from the song 'Summer Nights' - which is performed in the original movie by Travolta's Danny Zuko and Newton-John's Sandy Olsson as they recount a fling they had.

Haley is directing from a screenplay written by Leah McKendrick. Temple Hill and Picturestart are both producing.

'Grease' has entered popular culture for its iconic soundtrack and characters, with Sandy's girl squad The Pink Ladies' jackets and John's signature quiff and black leather jacket still a popular choice for fancy dress.

A sequel 'Grease 2' was released in 1982 and starred Michelle Pfeiffer, but it was poorly received and was criticised by Olivia.

Asked what she thought of 'Grease 2', the 71-year-old actress-and-singer previously said: ''Not a lot. They did ask us, I think they approached John and I to do it, and then it didn't happen, and I didn't think it was gonna happen, and then they made it with other people.''