An earthquake with a preliminary magnitude of 6.4 jolted Japan's northern island of Hokkaido on Saturday, the Japan Meteorological Agency said.

No tsunami was seen as a result of the quake and there were no reports of damage to local police as of 11:30 p.m. (1430 GMT), about 10 minutes after the quake occurred, public broadcaster NHK said.

There were no abnormalities at Tohoku Electric Power Co's Higashidori nuclear plant in northern Japan, NHK said, citing the utility.