Japan's Tohoku Electric Power has adequate electricity generation capacity to meet demand, a spokesman said on Monday, after a large earthquake at the weekend knocked out several big fossil-fuelled power stations.

The quake of magnitude 7.3 injured more than 150 causing damage throughout the northern region, including Fukushima, in a further test of a beleaguered electricity grid brought close to blackout last month by cold weather.

"As for today, we have enough supply capacity, but will continue to watch the situation carefully and consider measures to secure stable power supplies if needed," the spokesman told Reuters by telephone.

After the quake knocked out generation capacity, Tohoku Electric had been forced to seek electricity supplies from other regional utilities on Sunday, he said.

To satisfy demand, the company has restarted units halted before the quake, as well a 1 GigaWatt station that shut down automatically when the quake struck just before midnight on Saturday. It also shut two units for checks afterwards.

Wholesale prices of electricity have fallen to within the trading range on normal days, data on the Japan Electric Power Exchange showed, following Sunday's jump in the quake aftermath.

The Japan Meteorological Agency said the quake probably stemmed from greater seismic activity after the magnitude 9.0 earthquake of March 11, 2011 that set off a tsunami, killing nearly 20,000 people along a wide swathe of the northeast.

It also sparked the world's worst nuclear disaster in 25 years, when three reactors melted down at Tokyo Electric Power's Fukushima Daiichi station.

Last week's quake caused no incident at nuclear plants, none of which are operating in northern Japan.