Norwegian police are investigating a possible spying operation by a foreign power after electronic devices designed to intercept telephone conversations were discovered near government buildings.
In its own two-month investigation, the daily newspaper Aftenposten detected signals from several surveillance devices that had been placed near the prime minister's offices, the central bank, parliament and major company headquarters.
"We can't exclude the possibility that this is coming from foreign state agencies," said Siv Alsen, spokeswoman for the police's intelligence unit, which will carry out the investigation.
Aftenposten said the devices were able to attract mobile phone signals and record conversations.
"If correct, such surveillance is completely unacceptable," Justice Minister Anders Anundsen said in a statement. "We must make every effort to identify who or what is behind it, and how comprehensive it is."
Norway, a U.S. ally and a founding member of NATO, has had its share of diplomatic conflicts in recent years.
Its ties with China have been virtually frozen since 2010 when the Norwegian Nobel Committee awarded the Nobel Peace Prize to Chinese dissident Liu Xiaobo. Norway has also followed the European Union's sanctions against Russia this year.
Norway's military also patrols vast parts of the Arctic, monitoring commercial and military activity.