Japanese nuclear regulators said they raised the rating from 5 to 7 — the highest level on an international scale of nuclear accidents overseen by the International Atomic Energy Agency — after new assessments of radiation leaks from the Fukushima Dai-ichi plant since it was disabled by the March 11 tsunami.
The new ranking signifies a "major accident" that includes widespread effects on the environment and health, according to the Vienna-based IAEA. But Japanese officials played down any health effects and stressed that the harm caused by Chernobyl still far outweighs that caused by the Fukushima plant.
The revision came a day after the government added five communities to a list of places people should leave to avoid long-term radiation exposure. A 12-mile (20-kilometer) radius already had been cleared around the plant.
The news was received with chagrin by residents in Iitate, one of the five communities, where high levels of radiation have been detected in the soil. The village of 6,200 people is about 40 kilometers from the Fukushima plant.
"It's very shocking to me," said Miyuki Ichisawa, 52, who runs a coffee shop in Iitate. "Now the government is officially telling us this accident is at the same level of Chernobyl."
Japanese officials said the leaks from the Fukushima plant so far amount to a tenth of the radiation emitted in the Chernobyl disaster, but said they eventually could exceed Chernobyl's emissions if the crisis continues.
"This reconfirms that this is an extremely major disaster. We are very sorry to the public, people living near the nuclear complex and the international community for causing such a serious accident," said Chief Cabinet Secretary Yukio Edano.
But Edano told reporters there was no "direct health damage" so far from the crisis. "The accident itself is really serious, but we have set our priority so as not to cause health damage."