The formal announcement, expected from the government in coming days, would be the first official recognition that the March accident could force the long-term depopulation of communities near the plant, an eventuality that scientists and some officials have been warning about for months. Lawmakers said over the weekend — and major newspapers reported Monday — that Prime Minister Naoto Kan was planning to visit Fukushima Prefecture, where the plant is, as early as Saturday to break the news directly to residents. The affected communities are all within 12 miles of the plant, an area that was evacuated immediately after the accident.

The government is expected to tell many of these residents that they will not be permitted to return to their homes for an indefinite period. It will also begin drawing up plans for compensating them by, among other things, renting their now uninhabitable land. While it is unclear if the government would specify how long these living restrictions would remain in place, news reports indicated it could be decades.