South Korea's Ministry of Trade, Industry and Energy called on the nation Sunday to reduce power consumption amid a looming power shortage stemming from a sweltering heat wave in the country.

"All factories, public institutions, households and shops must refrain from using electricity between 10:00 a.m. and 6:00 p.m. for three days starting Monday," Minister of Trade, Industry and Energy Yoon Sang-jik said in a statement.

The call came after South Korea issued a warning for a possible power shortage Friday as high temperatures led to a surge in power consumption for cooling. Friday's warning was the second of its kind issued this year.

The preliminary warning was issued at 1:39 p.m. on Friday after the country's power reserves dipped to below 3.5 million kilowatts, the Korea Electric Power Corp. said in a released statement.

A light warning is issued when the power reserves fall below 4.5 million kilowatts, followed by a preliminary warning when the power reserves dip to below what is considered a safe level of 3.5 million kilowatts.

The ministry said the country's maximum electricity demand per hour is expected to hover above 80.5 million kilowatts next week, far exceeding its hourly power generation capacity of 77.4 million kilowatts.

Yoon said the country's power reverse level is expected to hover around the 1.8-million kilowatts mark even if all the government's measures to save energy are implemented.

"The current situation is grave, considering that a breakdown of a single power generator could lead to a recurrence of a massive blackout that took place in September 2011," said Yoon after presiding over an emergency meeting to cope with the power crisis.

He ordered the heads of state power monopoly Korea Electric Power Corp., its subsidiaries and related organizations to mobilize all contingency plans to head off a power shortage.

On Sept. 15, 2011, South Korea suffered massive blackouts due to unseasonably high temperatures that pushed up demand to what the authorities called "dangerous levels," forcing them to temporarily cut power to households and businesses.

At that time, around 1.62 million households across the country experienced temporary blackouts. (Yonhap News)