South Korea will invest 5.73 trillion won ($6.14 billion) to build two nuclear plants of 1.4 million kilowatts each by 2013-2014, Seoul's energy ministry said on Wednesday.

The plants will cut the use of fuel oil used for power generation by 4.2 million tones annually.

This is equivalent to saving 2.84 billion won per day on fuel oil, the ministry added.