Baku, April 12 (AZERTAC). Japan raised the severity rating of its nuclear crisis to the highest, matching the 1986 Chernobyl disaster, after increasing radiation prompted the government to widen the evacuation zone and aftershocks rocked the country.

Japan`s Nuclear and Industrial Safety Agency today raised the rating to 7. The accident at the Fukushima Dai-Ichi station was previously rated 5 on the global scale, the same as the 1979 partial reactor meltdown at Three Mile Island in Pennsylvania.

The stricken nuclear plant, located about 220 kilometers (135 miles) north of Tokyo, is leaking radiation in Japan`s worst civilian nuclear disaster after a magnitude-9 quake and tsunami on March 11. Tokyo Electric Power Co. said its plant, which has withstood hundreds of aftershocks, may spew more radiation than Chernobyl before the crisis is contained.

“If the leaks continue, the total radiation from the reactors may exceed” that from Chernobyl, Junichi Matsumoto, general manager of one of the utility`s nuclear divisions, said in Tokyo today.

The disaster at the Chernobyl power plant in modern-day Ukraine spewed debris as high as 9 kilometers into the air and released radiation 200 times the volume of the combined bombings of Hiroshima and Nagasaki in 1945, according to a 2006 report commissioned by Europe`s Green Party.

The radiation released so far is estimated to be around 10 percent of that from Chernobyl, Japan`s nuclear safety agency said earlier in a statement. The situation at the station is “severe but stable,” Hidehiko Nishiyama, the agency`s deputy director-general, said at a media briefing.

“We are trying to resolve the situation as soon as possible and will do our best to cool down the reactors and prevent the spread of radioactive substances,” Masataka Shimizu, president of the utility, a statement issued after the severity rating was raised. He also apologized for the accident.

The company`s shares fell 10 percent to close at 450 yen Tokyo. The stock has slumped 79 percent since the crisis began.

Prime Minister Naoto Kan said he has asked Tepco, as the utility is called, to give an assessment of when the company expects to resolve the crisis. “An outlook will be presented soon,” he said at news conference in Tokyo.

Today`s rating change won`t lead to a widening of the evacuation zone beyond the increase announced yesterday, Kenkichi Hirose, an adviser to Kan`s cabinet, said earlier.

Chief Cabinet Secretary Yukio Edano said yesterday that residents of some towns beyond the 20-kilometer evacuation zone around the plant will have a month to move to safer areas.

“In contrast with Chernobyl, we have been able to avoid direct health risks,” Edano said at a public event in Tokyo today. “The assessment level of 7 may be the same, but in terms of its shape and contents, the process has been different.”

The International Nuclear and Radiological Event Scale rates nuclear accidents in terms of their effects on health and the environment, according to the International Atomic Energy Agency, which helped set up the system. Each of its seven steps represents a ten-fold increase in the severity.

A 7 rating means there has been a “major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures,” according to the INES factsheet.

The assessment is based on the combined severity of the situation at reactor Nos. 1, 2 and 3, Nishiyama of the safety agency said.