Eight minutes of composer John Williams' Close Encounters of the Third Kind score that was cut from the 1977 film has been performed publicly for the first time.

The lost music was revealed in Brisbane on Saturday at the premiere of Close Encounters of the Third Kind in Concert — a screening of the science fiction movie with a live orchestra and choir.

Co-producer Jamie Richardson said the extra eight minutes of music was spread across the first and second acts.

"It's footage which was always in the film, it just didn't have music but Williams did write music originally for it," Mr Richardson said.

Mr Richardson said Williams and the film's director Steven Spielberg were involved in the concert's creative process.

"[Spielberg] is delighted with the approach we have taken," he said.

"When we prepare these projects it's very important for us to work not only with the composer but with the filmmaker."

Conductor Nicholas Buc, who led the premiere with the Queensland Festival Philharmonic orchestra and the Resonance of Birralee choir, said audiences would "geek out" over the collaboration of live music and film.

"It's a really great way of watching great films which we've known and loved for many years," Mr Buc said.

Producer Steve Linder, who has been involved in other live concert productions of Williams' scores including ET, Jaws, Raiders of the Lost Ark and Jurassic Park, said Close Encounters had always been on his wish list.

Mr Linder said bringing live music and film together transformed the experience from two-dimensional to three.

"We are always looking for interesting ways to present our films and broaden the reach of where an orchestra and film can go," Mr Linder said.

"[Music] provides dramatic arch, provides dramatic narrative and even in some cases, it's actually a character in the film."