Finnish Radiation and Nuclear Safety Authority said in a statement on Wednesday that trace amounts of radioactive material from Japan's nuclear accident have been detected in Finland, stressing that does not pose a health threat.

According to the statement, tiny amounts of the isotope iodine- 131, which was consistent with the releases from damaged reactors of the Fukushima nuclear plant in Japan, have been detected in the air samples from Finnish capital city Helsinki and the country's northernmost big city Rovaniemi.

However, the authority stressed that the level of radiation measured in Finland, which was no more than one millibecquerel in a cubic meter of air, was roughly one-millionth of the dose that could be harmful to human health. Therefore, people in Finland are not necessary to take any countermeasures for that.

The authority said in the statement that radiation pollution from the Fukushima nuclear plant is expected to spread in the whole Northern Hemisphere and other regions would be detecting the radioactive material later.