TOKYO — Japan’s nuclear regulators raised the severity level of the crisis at a stricken nuclear plant today to rank it on par with the Chernobyl disaster.

An official with the Nuclear Safety Commission of Japan, speaking on national television, said the rating was being raised from 5 to 7 – the highest level on the international scale.

The official, who was not named, said the amount of radiation leaking from the Fukushima Dai-ichi nuclear plant was around 10 percent of the Chernobyl accident.

Level 7 signifies a “major accident” with “wider consequences” than the previous level, according to the standards scale.

“We have upgraded the severity level to 7 as the impact of radiation leaks has been widespread from the air, vegetables, tap water and the ocean,” said Minoru Oogoda of Japan’s Nuclear and Industrial Safety Agency.

NISA officials said one of the factors behind the decision was that the total amount of radioactive particles released into the atmosphere since the incident had reached levels that apply to a Level 7 incident.

The action lifts the rating to the highest on an international scale designed by an international group of experts in 1989 and is overseen by the International Atomic Energy Agency.

In Chernobyl, in the Ukraine, a reactor exploded April 26, 1986, spewing a cloud of radiation over much of the Northern Hemisphere. A zone about 19 miles around the plant was declared uninhabitable .

Meanwhile, setbacks continued at Japan’s tsunami-stricken nuclear power complex, with workers discovering a small fire near a reactor building today. The fire was extinguished quickly, the plant’s operator said.

Tokyo Electric Power Co., which operates the disabled Fukushima Dai-ichi nuclear power plant, said the fire at a box that contains batteries in a building near the No. 4 reactor was discovered around 6:38 a.m. today local time and was put out at 6:45 a.m.

It wasn’t clear whether the fire was related to a magnitude-6.3 earthquake that shook the Tokyo area this morning.

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