Russia says a nuclear accident has not occurred on its territory despite “extremely high” traces of a radioactive isotope being found.

Russia’s weather service acknowledged it had measured pollution of ruthenium-106 at 1,000 times normal levels in the Ural mountains.

It said there was no health risk.

The announcement appeared to confirm a report by France’s nuclear safety institute which detected a cloud of radioactive pollution over Europe.

The Institute for Radioprotection and Nuclear Safety (IRSN) said on 9 November it had detected ruthenium-106 in France.

It added that the source of contamination could have been an accident at a nuclear facility in either Russia or Kazakhstan.

Both countries said nothing untoward had happened at their plants.

The report by the Russian meteorological service, Roshydrome, is the first official data from the country supporting the French report.

Roshydrome said two stations in the southern Ural mountains found “extremely high pollution” of the radioactive isotope between September and October.