TOKYO - An earthquake with preliminary magnitude 6.8 hit off eastern Japan on Saturday morning and a warning for a minor tsunami of up to one metre was issued for the northeastern coast, Japanese public broadcaster NHK reported.

There were no immediate reports of abnormalities at the crippled Fukushima nuclear power plant, which is in the area, NHK said.

The quake registered a moderate 4 on the Japanese seismic scale of 1-7, meaning that major damage was unlikely.