The Dutch National Institute for Public Health and the Environment (RIVM) said Sunday that "very low" levels of man-made radioactivity were found over the three countries. There was no impact on the environment or human health, it said.
"The combination of radionuclides may be explained by an anomaly in the fuel elements of a nuclear power plant," RIVM suggested after performing a calculation to find the source of the radionuclides, which are atoms with an unstable core.
"The calculations indicate that the nuclides come from the direction of western Russia. Determining a more specific source location is not possible with the limited data available," RIVM said on its website. It made clear that "no specific country of origin can be pointed out at this moment".
In response, Russia stated that no incidents were recorded at two plants in the west of the country.
"No incidents were recorded at the Leningrad nuclear power plant and the Kola nuclear power plant, both stations operate normally, there have been no complaints about the equipment's functionality," said a statement reported by state media outlet RIA Novosti from Rosenergoatom, part of the Rosatom state nuclear energy corporation that oversees all of Russia's nuclear infrastructure.