Japan's government has issued an advisory for possible power shortages in Tokyo and surrounding areas. It is the first such advisory announced under the country's new alert system.

Sweltering heat is expected to continue on Monday in the Kanto region, including Tokyo. Demand for electricity, such as the use of air conditioners, is expected to surge.

Government officials are calling on households and businesses in the areas to cut back on energy use as much as possible, especially between 3 and 6 p.m. on Monday.

But they also ask people to use air conditioners properly to prevent heatstroke.

Under the new alert system established in May, the government will issue an advisory at 4 p.m. That's when the reserve power-supply capacity is expected to drop below 5 percent the next day, even after additional supplies are offered by other regional utilities.

The government estimates that the reserve capacity will fall below 5 percent in the Greater Tokyo area on Monday. The rate will likely drop further to under 4 percent before 5 p.m.

Japan faces potential power crunches during extreme weather conditions due to a decline in power supply capacities at utility companies.

The Tokyo Electric Power Company, which services the Kanto region, says the utility's supply capacity has fallen as operations of some power plants in Fukushima Prefecture remain suspended due to the damage caused by an earthquake that hit the area in March.

The country also has aging thermal power plants that have been closed temporarily or permanently.