At least 15 people have been injured in a 6.9 magnitude earthquake that shook Tokyo early this morning.

A woman in her 80s broke her leg when she fell down the stairs and a woman in her 70s was injured when a cupboard toppled over.

People raced to higher ground as the quake hit off the north-east coast of Japan just before 6am local time.

The quake, which was initially put at a 7.3 magnitude, struck 67km northeast of Iwaki city, in the Fukushima Prefecture,the US Geological Survey (USGS) said.

The Japan Meteorological Agency issued tsunami advisories for much of the nation's northern Pacific coast.

After warnings were downgraded, the agency advised that another large quake could be expected within the next few days, and people in the region have been advised to “remain cautious” for the next week.

(Image: REUTERS) (Image: The Asahi Shimbun)

At the Fukushima Daini nuclear power plant the reactor number 3 spent fuel pool pump stopped operating at 6.10am as a result of the quake but is reported to be safe and "intact."

Its sister plant Fukushima Daiichi suffered a major nuclear meltdown in Japan's devastating 2011 quake.

Authorities said today's quake was an aftershock from Japan's 2011 quake, which was the most powerful ever recorded in the country and the fourth most powerful one in the world since records began in 1900.

The natural disaster, which triggered powerful 40m-high tsunami waves, claimed more than 18,000 lives and injured more than 6,000 people.