Quake near Japan's Fukushima plant

An earthquake has struck 34km east of Japan's Fukushima prefecture, where a devastating quake-tsunami in 2011 sparked a nuclear disaster.

A 5.1 magnitude earthquake has struck off the coast of Japan's Fukushima prefecture, the United States Geological Survey says.

The moderate quake hit 34 kilometres east of coastal Namie city in Fukushima prefecture, where a devastating quake-tsunami in March 2011 sparked a nuclear disaster and caused massive damage.

Saturday's earthquake occurred at 2.18am local time (6.18am AEDT) off the east coast of Japan's main Honshu island, at a depth of 63 kilometres, US geologists said in a preliminary report.

No tsunami warning was issued after the tremor, the Japan Meteorological Agency said, according to Kyodo news agency.