The Bellona Foundation called on Japan to cease all nuclear activity at all its plants until international investigators could sort through the cause of the accident.

“Japan should stop all its nuclear activities until an international independent investigation of the accident – including examining any erroneous information that was issued by Tokyo Electric – and should also consider future nuclear plans in light of the effects of the earthquake,” said Nils Boehmer, Bellona’s nuclear power expert.

On Wednesday, Tokyo Electric issued a statement saying that the leak of radioactive water was 50 percent worse than its initial assessment Monday, when it said 60,000 Bequerels of radioactivity had been released into the Sea of Japan when either 1.5 or 1,190 litres of water had sloshed out of Kashiwazaki-Kariwa’s No. 6 reactor.

On Tuesday, Tokyo electric finally confirmed that it had been 1,200 litres that had escaped, but added that 100 barrels of low-level radioactive waste had fallen over and a small amount of radioactive gas had been released into the air – but not until it had been pushed by Japanese Prime Minister Shinzo Abe, environmental groups and world media to be more definite.

After Wednesday’s statement by Tokyo Electric that the damage had been 90,000 Bequerels instead of 60,000, the mayor of nearby Kashiwazaki City ordered the plant to remain closed indefinitely.

But the firm insisted the leak was still well below danger levels. Yet, Mayor Hiroshi Aida said the plant could not reopen until its safety had been verified.

Mohamed ElBaradei, head of the UN’s International Atomic Energy Agency, or IAEA, called on Japan to investigate the incident to "make sure that we learn the necessary lesson from the earthquake."

Quake ‘beyond expectations’
In its statement, Tokyo Electric said there had been a “mistake” calculating the radioactive level of water that leaked into the sea.

It was 50 percent more radioactive than had been announced, the company said.

"But the corrected radioactivity is also below the legal limits and does not affect the environment," the statement read.

Despite Tokyo electics reassurances, the incident has triggered public concern and criticism of the company.

The seven-reactor plant – which is the world’s largest in terms of energy output – suffered more than 50 malfunctions and a fire in an electrical transformer as a result of Monday’s earthquake.

Tokyo Electric President Tsunehisa Katsumata has apologised for the incidents.

"I think we can say the size of the earthquake was beyond our expectations," he said as he visited the plant. Japan’s nuclear power plants are built to withstand tremors of 6.5 in magnitude, weaker than Monday’s quake.

"We regret what happened and will strive to make this a power plant that is safe," Katsumata said in remarks quoted by the BBC.

Japan is one of the most seismically active countries on earth. Some 30 percent of its energy consumption is supplied by 55 nuclear power plants.

The Kashiwazaki-Kariwa NPP is located close to the epicentre of Monday’s earthquake, which killed nine people, injured hundreds and flattened scores of homes.

Officials at Japan’s Meteorological Agency said that they were examining whether a fault line could stretch underneath the plant.

"We cannot deny the possibility" the plant sat on a fault, the Associated Press quoted the agency’s Osamu Kamigaichi as saying.

Tokyo Electric information suspect
In recent years, Tokyo Electric has damaged its credibility by covering up several nuclear incidents that could have been serious. A list of the seven accidents suffered over the past 10 years, compiled by AP, reveals the scale of fallibility that pervades Japan’s nuclear power industry.

– August 11th 2006: Tokyo Electric reports that a small amount of radioactive steam was released at the Fukushima Daiichi Nuclear Power Station in northern Japan on Aug. 6 and escaped outside the compound.

– August 9th 2004: Five workers at Mihama Nuclear Power Plant in western Japan are killed and six are injured after a corroded pipe ruptured and sprayed plant workers with boiling water and steam. The reactor was restarted on January 10th, 2007.

– February 25th 2004: Eight workers are exposed to low-level radiation at a power plant in Tsuruga, western Japan, when they are accidentally sprayed with contaminated water.

– September 17th 2003: Officials discover that about six litres of radioactive water had leaked from the No. 1 reactor at Chubu Electric Power’s Hamaoka plant in central Japan. In November 2001, the same reactor was shut down after two radioactive leaks occurred within three days.

– July 24th 2000: Tokyo Electric Power Co. finds 29 gallons of radioactive water leaking from a nuclear reactor at the Fukushima No. 1 plant in northern Japan days after an earthquake.

– September 1999: Two workers are killed in a radiation leak at a fuel-reprocessing plant in Tokaimura when they try to save time by mixing excessive amounts of uranium in buckets instead of using special mechanized tanks. Hundreds are exposed to radiation, and thousands of residents evacuate. The government assigned the accident a level 4 rating on the International Nuclear Event Scale. On the 1 to 7 scale, this incident was classified as a nuclear “accident” rather than an “incident.”

– March 1997: At least 37 workers are exposed to low doses of radiation at a March 11th fire and explosion at a nuclear reprocessing plant operated by Donen in Tokaimura, northeast of Tokyo.