A 6.2 magnitude earthquake has struck off Japan's eastern coast, causing buildings in Tokyo to sway.

There was no immediate danger of a tsunami being generated, the Japan Meteorological Agency said, and there were no immediate reports of injuries or damage.

"There may be a slight change in the sea level along the Japanese seacoast, but there is no concern over any damage" from potential high waves due to the quake, the agency said.

The earthquake occured at exactly 5pm local time (8:00 GMT) at a depth of 10km, with an epicentre 156km northeast of Tokyo, the United States Geological Survey said.

The Tokyo Electric Power Company (TEPCO) said the quake had caused no damage at the stricken Fukushima nuclear power plant, which was crippled after the March 11 9.0 magnitude earthquake and tsunami.

"So far no abnormality has been monitored in our water reprocessing and radiation monitoring systems," Hajime Motojuku, a spokesman for TEPCO, told the AFP news agency.

Tens of thousands of people remain evacuated from their homes in a 20km radius from the plant, from which radiation has been leaking since the disaster.

Sizeable aftershocks have continued to hit Japan since the March earthquake, but there have been no major tsunamis since then.

Japan is located at the junction of four tectonic plates, and experiences 20 per cent of the strongest earthquakes recorded every year.