Norway probes spy equipment found in central Oslo

Norwegian police said Sunday they have warned politicians about possible eavesdropping of cellphone calls after several listening devices were reportedly found in central Oslo, including near government buildings and Parliament.

Siv Alsen from the security police said the National Security Authority has begun an investigation, but could not provide more information pending the agency's report.

Espionage "has been high" in Norway for several years and police have told politicians to be on their guard, Alsen told the The Associated Press.

Her comments followed media reports that illegal listening and tracking devices were found in fake mobile base stations, which could be used to monitor calls and data, as well as trace the movement of people in the area.

The discovery followed an investigation by the daily Aftenposten, which used specially modified cellphones to detect the presence of fake mobile base stations, known as IMSI catchers.

"They did very meticulous work over more than two months," said Bjoern Rupp of Berlin-based company GSMK, which provided the modified cellphones.

"The journalists filtered out all the false positives and that still left some interesting sites," he said. Special locating devices were then used to pinpoint the exact whereabouts of the fake base stations.

Rupp said at least one of the devices found was so sophisticated and expensive that it had probably been placed there by a state actor.

The National Security Authority did not immediately return calls seeking comment.

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