Japan's Economy, Trade and Industry minister Banri Kaieda told reporters Sunday that a shortage in electricity supply may occur in northeastern and eastern Japan as nuclear power stations were paralyzed by Friday's great earthquake and ensuing aftershocks.

At a press conference, Kaieda said that utility companies such as the Tokyo Electric Power Co. (TEPOC) and Tohoku Electric Power Co. will carry out planned power cuts in their service areas to avoid massive power failures.

The measures may be implemented as early as Monday and will possibly last several weeks, he said.

The industrial minister said the government and utility providers will take every possible measure to minimize the impact of any planned outage on people's lives.

At a separate news conference, Chief Cabinet Secretary Yukio Edano called on the public to try their utmost to save energy.

He said that the government and power utilities will hold talks on the planned power outages later in the day.

The No.3 reactor at Fukushima No. 1 nuclear power plant lost its ability to cool the reactor core early Sunday, said the TEPOC, operator and owner of the Fukushima nuclear power plants.

The reactor became the sixth to lose the function after No.1 and No.2 reactors at the No. 1 plant and No.1, No.2 and No.4 at the No.2 plant had suffered the same trouble.

And Edano said earlier in the day that a hydrogen explosion is possible at the reactor.

The malfunctions at the power plants are the key factor behind the power supply shortage.