Radiation levels have risen dramatically in seawater near the stricken Fukushima nuclear plant in Japan, sparking fears of a new leak, according to the country's government.
The announcement came ahead of a fresh 5.9-magnitude earthquake that hit the Kanto region, in the eastern part of the country on Saturday morning.
Ironically the new quake hit hours after the country's nuclear safety agency ordered plant operators to beef up their quake alert systems to prevent a recurrence of the previous nuclear crisis.
New Leak: Volunteers arrive to clean up tsunami generated debris in Iwate prefecture, while radiation levels have risen dramatically in seawater near the stricken Fukushima nuclear plant
There were no reports of damage from the earthquake, and there was no risk of a tsunami similar to the one that struck the Fukushima Dai-ichi plant.
Since the earthquake and tsunami of March 11 knocked out the nuclear plant's cooling systems, workers have been spraying massive amounts of water on the overheated reactors.
Levels in the water had dropped, but on Friday levels of radioactive iodine-131 were found to have spiked to 6,500 times the legal limit.
Risk: Japanese police officers carry a body in Namie, Fukushima Prefecture, close to where radiation levels had rise 6,500 times above the legal limit
This was up from 1,100 times the limit in samples taken the day before.
Levels of cesium-134 and cesium-137 rose nearly fourfold. The increased levels are still far below those recorded earlier this month before the initial leak was plugged on April 5.
The new rise in radioactivity could have been caused by the installation on Friday of steel panels that were intended to contain radiation that may have temporarily stirred up stagnant waste in the area, Hidehiko Nishiyama of the Nuclear and Industrial Safety Agency told reporters.
Devastation: Two sisters look at a catamaran that was thrown onto a two-storey building during the tsunami, at Iwate prefecture, while a fresh 5.9-magnitude hit Eastern Japan on Saturday morning
However, the increase in iodine-131, which has a relatively short eight-day half life, could signal the possibility of a new leak, he said.
'We want to determine the origin and contain the leak, but I must admit that tracking it down is difficult,' he said.
Authorities have insisted the radioactivity will dissipate and poses no immediate threat to sea creatures or people who might eat them. Most experts agree.
String of disasters: A fire broke out at the stricken Fukushima nuclear plant last week, but was soon extinguished
Regardless, plant workers today began dumping sandbags filled with zeolite, a mineral that absorbs radioactive cesium, into the sea to combat the radiation leaks.
Meanwhile, the newspaper Asahi Shimbun reported, without citing its sources, that a secret plan to dismantle Tokyo Electric Power Co, which runs the radiation-leaking Fukushima plant, was circulating within the government.
The proposal calls for putting TEPCO, the world's largest private electricity company, under close government supervision before putting it into bankruptcy and thoroughly restructuring its assets.
In the wake of the nuclear crisis, the government ordered 13 nuclear plant operators to check and improve outside power links to avoid earthquake-related outages that could cause safety systems to fail as they did at the Fukushima plant, Nishiyama said.
Damage: Despite its size there were no reports of damage from the new earthquake, and there was no risk of another tsunami
The operators, including TEPCO, are to report back by May 16.
Power outages during a strong aftershock on April 7 drove home the need to ensure that plants are able to continue to operate crucial cooling systems and other equipment despite earthquakes, tsunamis and other disasters, Nishiyama said.
Utility companies were ordered to reinforce the quake resistance of power lines connected to each reactor or to rebuild them.
They also must store all electrical equipment in watertight structures. Earlier, the nuclear agency ordered plant operators to store at least two emergency backup generators per reactor and to install fire pumps and power supply vehicles as further precautions.
Still searching: A man looks for his lost belongings amongst tsunami devastation, as cherry blossoms bloom in Iwate prefecture
The massive 14-metre wave that swamped Fukushima Dai-ichi last month knocked out emergency generators meant to power cooling systems. Since then, explosions, fires and other malfunctions have compounded efforts by TEPCO to repair the plant and stem radiation leaks.
TEPCO said it had moved power sources for some of the reactors at the stricken plant to higher ground by Friday evening in order to avoid another disastrous failure in the event of a tsunami.
Goshi Hosono, an adviser to the prime minister and member of the nuclear crisis management task force, said the damaged reactors were much more stable than they had been earlier in the crisis and TEPCO was preparing to unveil a plan for restoring cooling capacity to the ailing reactors 'soon.'
'Problems are still piled up and we are far from the end of crisis,' he told a TV news programme, citing radioactive water as one of the biggest headaches.
'I expect there will be more mountains that we have to climb over.'
The crisis at the Fukushima plant has forced tens of thousands of people to evacuate the area, while radiation leaks have contaminated crops and left fishermen unable to sell their catches, adding to the suffering of communities already devastated by earthquake and tsunami damage.
Government officials fanned out across the affected areas to explain their decisions and calm nerves.
Deputy Chief Cabinet Secretary Tetsuro Fukuyama apologised for the uncertainty and confusion to residents in Litate village, parts of which the government recommended be evacuated because of the nuclear crisis.