Chinese waters have not yet been affected by leaks from Japan's quake-damaged Fukushima nuclear power station, but authorities are keeping a close watch on the possible long-term threats, the country's top oceanic official said in Beijing Sunday.

Liu Cigui, director of the State Oceanic Administration, said China has been conducting radioactive monitoring on its waters ever since a devastating earthquake and tsunami caused the Fukushima nuclear crisis in March last year.

Chinese oceanic authorities have expanded the area being monitored to include sea waters to the east of Japan in the western Pacific, and sent professional monitoring teams there in both June and December of last year, said Liu, who is also a deputy of the National People's Congress, the country's top legislature.

Leaks from the Fukushima nuclear plant have had significant influence on the marine space and lives in the waters of the western Pacific to the east and southeast of Japan, but it has not affected Chinese waters, as oceanic circulation draws most pollutants eastward, monitoring results have shown.

But considering the complicated small and mid-sized vortex motions in the marine space near Japan, some of the polluted water could be carried to the southwestern Pacific, which could pose threats to Chinese waters in the long run, said Liu.

Confirming and forecasting the flow of pollutants and their impact on the marine environment will therefore require long-term monitoring and evaluation, Liu added.