Predictions on the amount of radiation that had already been released from the crippled reactors, as well as further radiation that might escape into the atmosphere "could by no means be released to the public," says the document, according to Kyodo News.
Dated March 19, the document predicts that clouds of radioactivity could be released from the plant and spread across northern and central Japan, including Tokyo.
In another report released last week, an independent panel revealed that the government was drawing up plans to evacuate the 13 million residents of Tokyo at the same time as it was reassuring the public that there was no reason to worry about the situation at the nuclear facility.