The cinematic world was today celebrating the rediscovery of missing scenes from German director Fritz Lang's legendary silent film Metropolis - thought lost for 80 years, until they were found in the archive of a museum in Argentina.

Key scenes cut from the science fiction picture - either because they were considered to be too brutal or too long - will now be available for the first time since May 1927, when the original version was last shown in Berlin, where it flopped badly.

The head of the Berlin film museum Deutsche Kinematik, Dr Rainer Rother, called the find a "sensational discovery", adding that one of the most famous films of all time "can now be seen through new eyes".

Metropolis, which is set in a futuristic city state and explores the clash between workers and their capitalist exploiters, was at the time one of the most expensive films ever made. Produced in the Babelsberg studios on the outskirts of Berlin, it cost around 7m Reichsmarks, but was hated by critics and the public alike. It was shortened by the American company Paramount Pictures, who considered it impenetrable for the US market, leading to an oversimplification of the plot, the disappearance of key scenes and the sidelining of significant characters.

But the restored version, which has so far been seen by only a handful of film experts and critics in Berlin, is said to throw light on key questions that have puzzled and tantalised generations of film buffs.

The uncut version is said to solve the mystery as to why Maria, the workers' insurrectionist leader, is mistaken by a baying mob for her doppelganger, a female robot.

Schmale, a spy who is sent by the autocratic leader of the futuristic city, Joh Frederson, to pursue his son, Freder, plays a minor role in the cut version, but a significant supporting role in the original. "The role ... can finally be understood," Rother said.

A scene in which children are saved from the workers' underworld is also said to be "much more dramatic" - and more violent - than in the cut version.

The rediscovery, revealed by the newspaper Die Zeit, came to light after Paula Felix-Didier, curator of Buenos Aires' Museo del Cine, acted on a tip-off from a former film club director that the full-length version had been gathering dust in the museum's archive since the early 90s. Fearing that the discovery would not be taken seriously in Argentina, she flew with the footage to Germany this week to present the film to experts who have deemed it to be authentic.

Die Zeit has reconstructed the story of how the film found its way to Argentina. A copy of the longer version of the film was first sent to Buenos Aires in 1928 at the request of the Terra film distribution company. A film critic called Manuel Pena Rodriquez obtained the reels shortly afterwards, selling them in the 60s to Argentina's National Art Fund. A copy of them was passed onto the Museo del Cine in 1992, but their value was not fully realised until now.

Helmut Possman, director of the Friedrich-Wilhelm Murnau Foundation which holds the rights to Metropolis, said the film, which is badly scratched, would be made available to the public after it has been restored. "This material, which we had long considered to be lost forever, will help us to a new understanding of Fritz Lang's masterpiece," he said.

Martin Köerber, who restored a previous version of Metropolis, expressed his delight at the new footage.

He told Die Zeit: "It doesn't matter how bad the condition of the material is, the original intention of the film, including all of its minor characters and subplots, is now once again tangible for viewers. The rhythm of the film has been restored."