Tokyo has raised the severity level of its accident at the Fukushima Number One nuclear power plant to the highest level of seven.

The Japanese government's Nuclear Safety Commission made the call on Tuesday considering the massive amounts of radioactive materials released from the reactors in the Fukushima plant at one point.

The only other nuclear disaster to be labeled as a level seven, which is the highest severity level on the International Atomic Energy Agency’s International Nuclear and Radiological Event Scale, was the one at Chernobyl in 1986.

Earlier on March 18th, the Japanese Ministry of Economy, Trade and Industry's Nuclear and Industrial Safety Agency had tentatively estimated the incident at a level five, or the same level as the Three Mile Island accident in the United States in 1979.