Nokia paid several million euros to criminals who threatened to reveal the source code for part of its smartphone operating system seven years ago, a Finnish TV station has revealed.

Finnish police have confirmed that they are investigating an open case of alleged blackmail. Speaking to Reuters, Detective Chief Inspector Tero Haapala said “We are investigating felony blackmail, with Nokia the injured party.”

Nokia has not come forward with any comment on the case. Finnish TV station MTV (no relation to the music channel) is reporting that hackers acquired encryption codes for Nokia’s Symbian operating system, and had threatened to post them online.

If access to the Symbian source code had been made public, hackers could have injected potentially millions of smartphones with malware without fear of detection. The encryption key was used to prevent phones running unauthorized applications.

It has been reported by MTV that Nokia paid a multi-million euro ransom to the hackers, agreeing to deliver cash to a parking lot in Tampere in Finland. A police sting operation to catch the blackmailers picking up the money reportedly failed, as officers lost track of the criminals after they picked up the money.

At the time of the crime, Nokia had approximately 50% market share of mobile phones worldwide, with Symbian also used by other manufacturers. By 2006, 100m Symbian devices had been shipped. Since 2011, however, Nokia has shifted to Windows Mobile, and last year Microsoft purchased Nokia’s mobile phone division for a total of 5.4 billion euros.

Hackers have more and more often been demanding ransom from their targets. The malware Cryptolocker, which locks users out of their own files, has reportedly generated $1.1 million in Bitcoin payments by victims. Recently the news syndication app Feedly was hit by a denial-of-service attack in which the hackers responsible attempted to extort payment to restore access to the site.