Japan’s prime minister has made a public appeal for calm after the nuclear plant crisis was raised to the highest alert level - on par with the 1986 Chernobyl disaster.
Prime Minister Naoto Kan urged people in a televised address to focus on recovering from the country’s disasters.
Mr Kan said: “Right now, the situation of the nuclear reactors at the Fukushima plant has been stabilising step by step. The amount of radiation leaks is on the decline,” he said. “But we are not at the stage yet where we can let our guards down.
“Let’s live normally without falling into excessive self-restraint,” he said.
“We should eat and drink products from the quake-hit areas as a form of support.”
Japanese regulators said they raised the rating from 5 to 7 - the highest level on an international scale - after new assessments of radiation leaks from the Fukushima Dai-ichi plant.
The higher rating is an open acknowledgement of what was widely understood already: The nuclear accident is the second-worst in history. It does not signal a worsening of the plant’s status in recent days or any new health dangers.
However people living nearby who have endured a month of spewing radiation and frequent earthquakes said the change added to their unease despite government efforts to play down any notion that the crisis poses immediate health risks.
The new ranking signifies a major accident that includes widespread effects on the environment and people’s health. The scale, designed by experts convened by the IAEA and other groups in 1989, is meant to help the public, the technical community and the media understand the public safety implications of nuclear events.
The upgraded status did not mean radiation from the plant was worsening, but rather reflected concern about long-term health risks as it continues to spew into the air, soil and seawater.
Workers are still trying to restore disabled cooling systems at the plant, and radioactive isotopes have been detected in tap water, fish and vegetables.
Japanese officials said the leaks from the Fukushima plant so far amount to a tenth of the radiation emitted from Chernobyl, but about 10 times the amount needed to reach the level 7 threshold. They acknowledged the emissions could eventually exceed Chernobyl’s, but said the chance that will happen is very small. However, regulators have also acknowledged that a more severe nuclear accident is a distinct possibility until regular cooling systems are restored - a process likely to take months.
In Chernobyl, in what is now the Ukraine, a reactor exploded on April 26, 1986, spewing a cloud of radiation over much of the Northern Hemisphere. A zone about 30km around the plant was declared uninhabitable.
Thirty-one men died mostly from being exposed to very high levels of radiation trying to contain the accident. But there is no agreement on how many people are likely to die of cancers caused by its radiation.
No radiation exposure deaths have been blamed on the leaks at Fukushima Dai-ichi. Two plant workers were treated for burns after walking in heavily contaminated water in a building there.
A spokesman for Japan’s Nuclear and Industrial Safety Agency, noted that unlike in Chernobyl there have been no explosions of reactor cores, which are more serious than hydrogen explosions.
“In that sense, this situation is totally different from Chernobyl,” he said.
NISA officials said they raised the incident level because of the cumulative amount of radioactive particles released into the atmosphere. Other factors included damage to the plant’s buildings and accumulated radiation levels for its workers.
Work to stabilise the plant has been hampered by continued aftershocks, the latest a 6.3-magnitude quake that prompted plant operator Tepco, to temporarily pull back workers.