Russia has denied that a spike in radioactive levels across Europe was due to a nuclear facility leak, saying the increase was instead caused by a satellite that burned as it re-entered Earth's atmosphere.

Greenpeace Russia had alleged that a leak of ruthenium-106 came from a nuclear facility in Mayak, which is 100 km outside the city of Chelyabinsk, in eastern-central Russia. However, state-run Russian news agency TASS on Friday said an inquiry panel found there were no traces of ruthenium-106 at the Mayak Combine.

"Examination of test samples identified no presence of ruthenium-106. The strength of gamma radiation and the intensity of beta rays are at the natural background level," said the panel statement.

The nuclear facility also denied involvement in the atmospheric spread of the radioactive material, saying "no sources have been manufactured from ruthenium-106 at the plant in 2017".

IRSN, a French-based nuclear safety institute, previously said the material detected was more likely to have been released from a nuclear fuel treatment site or centre for radioactive medicine than from an accident in a nuclear reactor.

Questions surrounded Russia after IRSN said in November there was a spike in "radioactive contamination" between September 27 to October 13, adding that ruthenium-106 was detected in the atmosphere of the majority of European countries.

The contamination, however, was not enough to cause environmental or health risks, according to IRSN.

Traces of ruthenium-106 in Europe were no longer detected in November.

The Mayak site is one of the largest nuclear facilities in Russia. In 1957, a waste tank exploded at the plutonium production facility and forced the evacuation of some 10,000 nearby residents, making it one of the worst nuclear accidents, alongside Chernobyl and Fukushima.