MOSCOW (AP) -- Russian authorities on Tuesday confirmed reports of a spike in radioactivity in the air over the Ural Mountains while the suspected culprit, a nuclear fuel processing plant, denied it was the source of contamination.
The Russian Meteorological Service said in a statement Tuesday that it recorded the release of Ruthenium-106 in the southern Urals in late September and classified it as "extremely high contamination."
France's nuclear safety agency earlier this month said that it recorded radioactivity in the area between the Volga River and the Ural Mountains from a suspected accident involving nuclear fuel or the production of radioactive material. It said the release of the isotope Ruthenium-106 posed no health or environmental risks to European countries.
At the time, Russia's state-controlled Rosatom corporation said in a statement that there had been no radiation leak from its facilities.
The Russian meteorological office's report, however, noted high levels of radiation in residential areas adjacent to Rosatom's Mayak plant for spent nuclear fuel. Air samples in the town of Argayash in late September-early October, for example, showed levels nearly 1,000 times higher than those recorded in the previous months.
The Russian Natural Resources Ministry which oversees the meteorological office in a statement later on Tuesday sought to reassure the public, claiming that the radiation levels there still were lower than those deemed to be dangerous.
Mayak in a statement on Tuesday denied being the source of contamination. The plant said it has not conducted any work on extracting Ruthenium-106 from spent nuclear fuel "for several years."
Mayak, in the Chelyabinsk region, has been responsible for at least two of Russia's biggest radioactive accidents. In 2004 it was confirmed that waste was being dumped in the local Techa River. Nuclear regulators say that no longer happens, but anti-nuclear activists say it's impossible to tell given the level of state secrecy.
In 2016, Associated Press reporters visited a village downstream from Mayak where doctors have for years recorded rates of chromosomal abnormalities, birth defects and cancers vastly higher than the Russian average. A Geiger counter at the riverbank in the village of Muslyumovo showed measurements 80 to 100 times the level of naturally occurring background radiation.
A decades-long Radiation Research Society study of people living near the Techa River, conducted jointly by Russian and American scientists, has linked radiation particularly to higher rates of cancer of the uterus and esophagus.
The Nuclear Safety Institute at the Russian Academy of Sciences, which oversees safety standards for the country's nuclear industry, has insisted, however, that Mayak's nuclear waste processing system presents no danger to the surrounding population.
Environmental pressure group Greenpeace said in a statement on Tuesday that it would petition the Russian Prosecutor General's office to investigate "a possible concealment of a radiation accident" and check whether public health was sufficiently protected.