Two moderate earthquakes struck off Japan's eastern coast near Fukushima early Monday, the US Geological Survey said, but officials said there was no immediate risk to the stricken power plant.

The epicentre of the first quake, with a magnitude measuring 5.7, was located some 91 kilometres (56 miles) off the coast of Honshu, Japan's largest and most populated island, at a depth of 22 kilometres shortly after 3:00am local time (1800 GMT Sunday).

A second, 5.6-magnitude quake struck two hours later slightly closer to shore at a depth of 39 kilometres. Cities nearest to the epicentre included Iwaki, Kitaibaraki, Namie and Hitachi, USGS said.

The same coastline was struck by a devastating quake and subsequent tsunami in 2011 that killed more than 18,000 people and sparked a meltdown at the Fukushima power plant -- the world's worst nuclear accident in a generation.

Tokyo Electric Power Company (Tepco), which runs the Fukushima plant, said in an email that it had found no anomalies at the site following the quakes. Two other plants in the region also reported no problems.

Trains continued to operate normally and no damage or injuries were reported, the NHK broadcaster reported.

The Japan Meteorological Agency put the magnitude of the first quake on Monday slightly higher at 5.8, adding that there was no immediate risk of a tsunami.

Japan is situated at the conjuncture of several tectonic plates and experiences a number of relatively violent quakes every year.

But thanks to strict building codes, even powerful quakes that might wreak havoc in other countries frequently pass without causing much damage.

Overnight Sunday, a moderate 5.6-magnitude quake struck northern Honshu with no damage reported. Last month a strong 6.0-magnitude earthquake shook buildings in the Japanese capital Tokyo, injuring 17 people.