At 3:00 p.m. (0600 GMT), about 270,000 customers still had no electricity, the company said.

"The weather is not improving, so we cannot get to the sites and make repairs," a Tohoku spokesman said. "It is a difficult situation."

Some 1,000 traffic lights had gone out in Niigata city, and television footage showed empty streets. Most trains in the prefecture, including the high-speed bullet train linking it with Tokyo, were halted temporarily due to the outage.

In the western prefecture of Fukui, two nuclear power plants automatically shut down because of technical problems with electric transmission systems caused by the heavy snow, but the reactors were not damaged and there was no radiation leak, their operator, Kansai Electric Power Co. said.

Some of the heaviest snowfall on record for this time of year has hit the country since last week, even in some southern prefectures that rarely see snow, but has spared Tokyo.

In northern Niigata, snow had piled up as high as 184 cm (72 in). The Meteorological Agency expected more snow in the coming days, and warned people in affected regions to take precautionary measures.

In South Korea, snow in the southern and southwestern areas claimed at least three lives, stranded thousands of motorists and damaged hundreds of greenhouses, local media reported.

Several thousand South Korean troops had been deployed to clear highways and remove snow from the roofs of structures to prevent collapse, the reports said.

South Korean officials said damage has been estimated at about $220 million.

About 40 cm to 50 cm of snow have fallen in the past day in parts of the region. Meteorologists said more snow would hit the southwestern parts of the country on Friday.