German officials say that a spike in radioactivity has been detected in the air in western and central Europe. Elevated levels of the isotope Ruthenium-106 have been reported in Germany, Italy, Austria, Switzerland and France since September 29. The source of the Ruthenium-106 is still unknown, but calculations indicate it may have been released in eastern Europe. Experts from Germany's Federal Office for Radiation Protection (FORP) raised the alarm yesterday, after five Weather Service stations detected traces of the particle. This follows air monitoring stations across the continent recording an increase in the isotope. The levels detected are low, 17,000 times lower than the limit set for this particle, and do not pose a threat to human health as of yet. Officials added that the source could not be an accident at a nuclear power plant. In a written statement, a spokesman said: 'New analyses on the source of the radioactive substance ruthenium-106 suggest a release in eastern Europe, at a distance of more than 1,000 kilometres (620 miles) from Germany. 'Since only ruthenium-106 has been detected, an accident in a nuclear power plant can be excluded as a cause. 'With this small amount of radioactivity there is no health hazard to the population.' Ruthenium is part of the platinum group of metals. Ruthenium-106 is an isotope, or variant with a different number of neutrons in its nucleus, used for radiation therapy to treat eye tumours. It is sometimes as a source of energy, known as radioisotope thermoelectric generators, used to power satellites.