Police investigator Bent Isager-Nielsen said officers searched the homes of Ken B Rasmussen and Kasper Kopping, who used to work for Se og Hoer magazine, to find more evidence. They also raided the offices of a media group and a book publisher.
Rasmussen, who was laid off in 2012 as part of sweeping staff cuts, relates in a recently published book how reporters used information from a secret source at IBM with access to a card-payment company's computers.
Rasmussen said that the magazine had paid the informant 1,840 USD a month for the leaks, but declined to give more information about him.
He said their techniques were far superior to those used by reporters at the now-defunct British tabloid News of the World which was engulfed in a phone hacking scandal, describing those as "pure boy scout methods" in comparison.
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The suspects face a maximum prison sentence of six years if found guilty, but have only been provisionally charged by the police, a step short of formal charges.