A report commissioned by the government found that current knowledge of thorium-based energy production and the geology of the natural resource are not solid enough to draw any conclusions about the potential value to Norway.
"Technically there is plenty of thorium, but what are the economics of thorium? That we do not know," Mikko Kara, a Finnish professor who led the study, told a news conference.
Reports that Norway has the world's third-biggest thorium resources have sparked discussion about its potential and prompted one Norwegian start-up, Thor Energi, to propose building a thorium-based nuclear power plant in Norway.
Though thorium energy is more expensive than conventional nuclear plants fired by uranium, and the technology is still being pioneered, burning thorium results in less radioactive waste and it cannot be used to produce atomic weapons.
So far only India is taking concrete steps to develop thorium-based nuclear power generation.
Some environmentalists have criticised the idea of exploiting Norway's thorium, saying it has detracted from the search for renewable energy sources and led people to believe thorium is a "free lunch."
Kara said that assessments of the size of the resources were contradictory, as the U.S. Geological Survey estimated Norway has a reserve base of 150,000 tonnes -- making it the world's third-biggest after Australia's and India's -- but he said that the Norwegian Geological Survey had "a more realistic picture."
"It is essential to assess whether thorium in Norwegian rocks can be defined as an economical asset for the benefit of future generations," Kara said, adding that that meant looking ahead 20-30 years.
Oil and Energy Minister Aaslaug Haga said that the report was meant to boost the level of knowledge about thorium, not to open a debate on whether Norway should adopt nuclear power.
Rich in hydropower and offshore oil and gas, Norway has no atomic power plants, unlike its Nordic neighbours Sweden and Finland. Norwegians tend to be sceptical about nuclear power.
"We have formidable potential to develop renewable energy," Haga said, adding that Norway should continue to avoid the risks associated with nuclear power production.
Kara told Reuters that he could not imagine a situation where Finland's nuclear power plants would be converted to thorium, and added that uranium-based generation will remain the mainstream of atomic power development internationally.
He said that thorium can effectively be used as a component of mixed fuels with uranium, but he said that the safety aspects of thorium did not put it ahead of uranium as a fuel.
