At the same time, the head of Rosgidromet said that the automatic monitoring system detected an increase in the concentration of Ru-106 not only in Russian Federation, but also in neighboring countries such as Poland, Romania, Bulgaria and Ukraine.
Alarmingly high radiation levels nearly 1,000 times above normal levels have been detected in the Ural mountains, according to Russia's meteorological service.
Russia's meteorological service has confirmed "extremely high" concentrations of the radioactive isotope ruthenium-106 in the country in late September.
Following the initial reports, Russia's state-controlled Rosatom corporation had said in a statement last month that the radiation had not come from its facilities. Today it is used for the processing of nuclear fuel waste.
The announcement appeared to confirm a report by France's nuclear safety institute which detected a cloud of radioactive pollution over Europe.
A station close to the Mayak nuclear facility in Chelyabinsk region indicated levels 986 times those of the previous month, it said, without specifying the origins of the pollution. In mid-October, it issued a statement saying "in samples tested from September 25 to October 7, including in the southern Urals, no trace of ruthenium-106 was found, except in Saint Petersburg".
The confirmation largely matched the earlier assessment of French authorities, but Rosatom continues to dispute that it is responsible for the high radiation levels, although it operates a nuclear reprocessing plant in the area.
Ruthenium is part of the platinum group of metals.
Russia Admitted about Radioactive Contamination over Europe in September
"An emergency discharge of ruthenium could be connected with the process of nuclear waste vitrification", the Russian arm of the NGO said.
It said that the source of the pollution was probably an accident somewhere between the Volga River and the Ural Mountains, adding that the concentrations measured in Europe were not a danger to public health. It added the isotope was detected in Tatarstan and southern Russian Federation, eventually reaching "all European countries, starting in Italy and toward the north of Europe" from September 29.
The mysterious cloud was spotted in September and October and European reports blamed it on nuclear contamination from Russian Federation.
It had also said the levels recorded in Europe were of "no outcome for human health and for the environment".
It has prompted demands by Greenpeace's Russian Federation branch for a more "in-depth inquiry".
The French institute said a nuclear reactor could not have been the source of the Ru-106 as other radioactive elements would also have been detected.
"Greenpeace will send a letter asking prosecutors to open an inquiry into potential concealment of a nuclear incident", the charity said in a statement.
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