The long-lost "director's cut" of a cinematic masterpiece has been found in Argentina.

The discovery of Fritz Lang's Metropolis is being hailed as miraculous by enthusiasts of the Vienna-born director and his 1927 science-fiction epic, renowned for its special effects including the robot woman Maria.

The original 3½-hour film was thought to have been lost when its US distributor, Paramount, cut it by 30 minutes after a poor reception from critics. But the German newspaper Die Zeit has reported that a copy of the original was sent to Argentina in 1928, where it has since gathered dust in the Buenos Aires Film Museum.

The film charts a class struggle in a dystopian futuristic society and was the first to be placed on UNESCO's Memory of the World Register, which preserves cultural landmarks.

It was not a commercial success and nearly ruined the studio behind it, and Metropolis still ranks as one of the most expensive films made after inflation is taken into account.

The "lost" footage, some of which is badly scratched, includes battle scenes and sections that flesh out a number of subplots and characters.

Paula Felix-Didier, the curator of the museum, viewed the film only after a chance remark from a projectionist, who noted that it was longer than other versions.

A film restorer who has seen the new footage said the film had its rhythm back.

Telegraph, London