Six men have been arrested over a dramatic helicopter raid on a Swedish cash storage depot, a court said Monday, in which millions of dollars were reportedly stolen.

One of the six suspects, aged between 21 and 38, is the alleged pilot in the airborne raid which saw an armed gang jump from a stolen helicopter into the centre Wednesday before making off with sacks stuffed with banknotes.

Five are accused of violent robbery while the sixth is accused of being an accomplice, according to official documents from the prosecutor of the Stockholm court sent to AFP.

Swedish newspaper Expressen said the amount stolen was 65 million kronor (6.3 million euros, 9.2 million dollars), without citing a source.

Security firm G4S, which runs the storage centre, has offered seven million kronor (680,000 euros, 995,000 dollars) for information on the case.

Early Wednesday masked men launched the assault in the southern Västberga suburb of the Swedish capital, dropping onto the roof of the banknote storage facility from the helicopter.

The masked men then smashed a window and blasted their way through the building using explosives before exiting the building several minutes later with sacks of cash.

The robbers carried out the raid in front of police and 21 workers present in the centre.

The helicopter, which was stolen shortly before the raid, was recovered undamaged several hours later north of Stockholm.