Rise in radioactivity across Europe puzzles scientists

The measurements show an increase in the isotope, Ruthenium-106

(File image) The radioactive material went missing from an oil company's storage facility (Getty Images)

A spike in radiation levels across five European countries in less than a fortnight has left officials baffled.

Germany, Italy, Austria, Switzerland and France have all seen a slight increase in radioactivity measured in the air since 29 September.

Taken by Germany’s Office for Radiation Protection, the measurements show an increase in the isotope, Ruthenium-106.

The low levels do not pose a threat to human health and the organisation also stressed that the source could not be an accident at a nuclear power plant.

But officials do not known what has caused the elevated radiation levels, although they believe they may have originated from Eastern Europe.

The isotope Ruthenium-106 is commonly used in chemotherapy to treat eye tumours.

It is also used in radioisotope thermoelectric generators (RTGs), which provide power to satellites.

Scientists claim it is one of the more stable and least dangerous, ruthenium isotopes.