JOIN USThe east of the country is likely to face substantial shortages after the massive quake hit on Friday, Economy, Trade and Industry Minister Banri Kaieda said at a news conference.
The region is covered by Tokyo Electric Power (Tepco) and Tohoku Electric Power.
In Tepco's case, its service region will be divided into five blocks and each area will have rolling blackouts for three hours a day by rotation, the Agency for Natural Resources and Energy said.
Such scheduled blackouts are expected to continue for several weeks, Tetsuhiro Hosono, chief of the agency, told a press conference.
He added Tepco was expected to be about 25 per cent short of its normal power supply for the time of year.
For Tohoku-Electric Power Co., which covers the northern region of Japan's main island, the scale of its expected power shortage would depend on how quickly the region and its industries can be rebuilt.
The immediate prospects for Japan's atomic power industry are a key concern following a radioactive leak and explosion at a plant yesterday.
The Japanese nuclear industry provides around 30 per cent of Japan's power needs.
In total, 11 of the roughly 50 nuclear reactors in Japan, located in the worst affected areas, shut down following the earthquake.