Carmakers will work over the weekend and take two days off during the week to save energy amid power shortages caused by Japan's quake-tsunami disaster, an industry body said Thursday.

Factories will be closed on Thursday and Friday from July to September as the country faces the prospect of blackouts in the wake of the March 11 twin disasters that devastated Japan's northeastern coast and shattered infrastructure.

"The automakers and autoparts makers have decided to shift our holidays from Saturdays and Sundays to Thursdays and Fridays," Toshiyuki Shiga, the chairman of the Japan Automobile Manufacturers Association, said at a press conference.

Electricity consumption is generally higher during the week than at the weekend.

"On Saturdays and Sundays, power supplies are adequate and we can conduct production without limitations," Shiga added.

Some companies may also direct back-office staff to take their days off during the week, Shiga said, adding that Japanese car manufacturers aim to "limit power consumption without disruption to production".

The quake and tsunami has forced numerous temporary factory shutdowns -- meaning shipments of key parts to China also stopped.

Japan's domestic sales of new cars, trucks and buses logged their biggest-ever drop in April as the disaster hit production and supplies to dealers.

Japanese auto maker Toyota said last month it would slash output at its Chinese plants by 50-70 percent until June 3 due to a shortage of parts.