The target will be in place until Sept, 22 for areas served by Tepco and until Sept, 9 for those covered by Tokyo Electric, he added. It will apply between 9 a.m. and 8 p.m. on weekdays - AP (File Photo )

TOKYO: A target to cut electricity use by 15 per cent in regions affected by Japan's March 11 earthquake and tsunami will take effect from July 1 and last more than two months, the top government spokesman said on Wednesday.

The cuts are aimed at helping avoid power blackouts during the peak summer demand period amid efforts to restore generating capacity lost in the disaster.

They apply to areas covered by Tokyo Electric Power Co, known as Tepco, which serves the capital and surrounding region, and Tokyo Electric Power Co, serving the devastated northeast region.

Chief Cabinet Secretary Yukio Edano told a news conference the measure will affect big power consumers but not medical institutions.

The target will be in place until Sept, 22 for areas served by Tepco and until Sept, 9 for those covered by Tokyo Electric, he added. It will apply between 9 a.m. and 8 p.m. on weekdays.

The 15 per cent cut is compulsory for large industrial users with contracts to consume 500 kilowatts or more, which Tepco says account for one-third of peak demand. Other firms and households are urged to make voluntary cuts by the same margin, with lower targets for hospitals and public transport.

The tsunami knocked out several nuclear and thermal power stations, triggering a crisis at Tepco's Fukushima Daiichi plant, where engineers are still struggling to control reactors that had fuel meltdowns and stop radiation leaks that have led to thousands of residents being evacuated.

Among steps to curb power use during the hot summer months, when air-conditioning causes demand to spike, car and car parts makers have decided to temporarily switch days off to weekdays instead of weekends, running factories instead on Saturdays and Sundays when power demand is lower.