The operator of the Fukushima nuclear plant has ordered workers near the coast to move to higher ground after a 7.6 magnitude earthquake, Japanese broadcaster NHK reported.
Japan's emergency agencies have declared a tsunami warning for the region that includes the crippled nuclear site.
All but two of Japan's 50 reactors have been offline since a magnitude-9.0 earthquake in March 2011 triggered a tsunami which led to massive radiation leaks at the plant 160 miles northeast of Tokyo.
A powerful 7.6 magnitude earthquake has been recorded 231 miles east of Japan's Honshu island, the US Geological Survey said.
The Japanese weather agency issued a yellow warning for a 1m tsunami in Japan's Fukushima region, due to hit the coast at 6.42pm UK time.
Japan's top government spokesman has said that the country's fish exports are safe for consumption because of the stringent inspection procedure in place.
The comment was made after South Korea said it is banning all fishery product imports from eight Japanese prefectures, including Fukushima, due to concerns about radiation contamination from the crippled Fukushima nuclear power plant.
An earthquake in southern Japan has not led to any irregularities at the stricken Fukushima nuclear plant, according to the company that runs the plant.
Initial readings from the US Geological Survey show that the earthquake had a magnitude of 6.4.
After two years of radioactivity leaking into the sea, Japan has at last announced a revolutionary and untested plan to stop the flow from a damaged nuclear power plant.
It involves an underground wall of ice.
ITV News Science Editor Lawrence Mcginty has more:
A large part of the new funding announced by the Japanese government will go towards freezing the ground around the Fukushima nuclear plant to contain the leak, according to local press reports.
The process, which is expected to cost 32 billion yen, will involve burying vertical pipes in the ground around the plant and pumping refrigerant through them.
Around 15 billion yen will go towards treating the contaminated water being stored at the plant.
The Japanese government has pledged 47 billion yen (£303m) to contain leaks at the crippled Fukushima nuclear plant, a government spokesman has said.
It follows the detection of a serious leak from one of the storage tanks containing contaminated water on site.
"The contaminated water problem is getting more critical by the day, and the government felt it was essential to become involved to the greatest extent possible," Chief Cabinet Secretary Yoshihide Suga said.
He said that the funds would be used for a water containment wall and decontamination.
Radiation at a tank holding highly contaminated water at Japan's crippled Fukushima nuclear plant has spiked 18-fold, the plant's operator has said.
Radiation of 1,800 millisieverts per hour - enough to kill an exposed person in four hours - was detected near the bottom of one storage tank on Saturday, Tokyo Electric Power Co , also known as Tepco, said.
A Tepco spokesman also said a new leak had been detected from a pipe connecting two other tanks.
The Fukushima plant was destroyed by a tsunami in March 2011 in the worst nuclear disaster since Chernobyl a quarter of a century earlier.
International concern is growing over the leak of highly radioactive water from the Fukushima nuclear plant in Japan. The danger level has been raised from one to three, the highest level since the tsunami caused a meltdown, two years ago.
The leak is the latest in a series of growing safety concerns at the plant, as ITV News Correspondent Paul Davies reports.
Japan's nuclear watchdog has criticised the safety checks by plant workers at the Fukushima Dai-ichi plant. The comments come as it emerged hundreds of tonnes of highly radioactive water leaked from the plant into the Pacific Ocean. The leak is the fifth such incident in a year.
Officials said workers apparently overlooked several signs of the leaks - and suggested that the twice-daily patrols recorded were largely just a walk. Water levels inside tanks were not monitored, and the puddle that caused this latest leak was not detected, until it was too late.
Watchdog chairman Shunichi Tanaka said another radioactive leak into the sea is a real fear, and steps must be taken immediately to safeguard the plant.
That's what we fear the most. We must remain alert.
We should assume that what has happened once could happen again, and prepare for more. We are in a situation where there is no time to waste.