Norway's intelligence services said it - and not the U.S. National Security Agency, as reported in a Norwegian newspaper - kept records on more than 33 million phone conversations over the space of one month last winter, Oslo said on Tuesday.
The daily Dagbladet said the U.S. NSA spied on close NATO ally Norway, collecting data about Norwegian phone conversations last December and January.
"This is data collection by Norwegian intelligence to support Norwegian military operations in conflict areas abroad, or connected to the fight against terrorism, also abroad," Lieutenant General Kjell Grandhagen, head of the Norwegian Intelligence Service, told a news conference.
"This was not data collection from Norway against Norway, but Norwegian data collection that is shared with the Americans."
Dagbladet's report, based on documents made public by fugitive former NSA contractor Edward Snowden, was co-authored by Glenn Greenwald, the former Guardian journalist who brought Snowden's leaks to world attention.