A 5.5-magnitude earthquake hit Japan's Fukushima area on Monday, but a nuclear plant there that was crippled by a huge quake and tsunami in March remained stable, officials said.

The offshore quake struck at 11:45 am (0245 GMT) beneath the Pacific off Fukushima prefecture in the country's north, at a depth of 30.2 kilometres (18.8 miles), the US Geological Survey said.

A tsunami was not expected, said the Japan Meteorological Agency, while there were no reports of damage.

Nuclear plant operator Tokyo Electric Power Co. (TEPCO) said that the stricken Fukushima Daiichi nuclear plant remained stable.

"We are not seeing any new abnormality" at the facility, where work is ongoing to bring reactors to a cold shutdown by the end of this year, a TEPCO spokesman said.

Skyscrapers in Tokyo, some 245 kilometers (152 miles) away, were slightly rocked by the tremor.

A 9.0-magnitude earthquake on March 11 triggered a monster tsunami which killed some 20,000 people and crippled the cooling systems at Fukushima, causing meltdowns in some of its reactors.

Radiation leaked into the air, soil and sea around the plant, forcing tens of thousands of people to evacuate their homes.

Hundreds of powerful aftershocks have shaken the region since the March quake.