The Art & Culture Trust of Sikkim, a private body working for the preservation of ethnic Sikkimese art and culture, said they would move high court to stop the film's screening.
"The Bengal government cannot screen the film without seeking our permission when the copyrights are with us. Even the censor certificates are with us. We are going to court to take a stay order on its screening," Ugyen Chopel, managing trustee of the body, told PTI from Gangtok.
Claiming exclusive possession of a sole 35 mm print and two DVD versions of the film, he alleged that the film festival authorities were only showing a pirated version of the much-talked-about documentary.
"If they are screening it without taking a copy from us, that means they have a pirated version, which is completely illegal," he said adding that they had planned to organise a gala premiere of the film in Gangtok in March, next year.
'Sikkim' is scheduled to be screened from tomorrow in the eight-day KFF, which will be kicked off later in the day.
The authorities have, however, decided to go ahead with the screening.