Korea Midland Power Co. Ltd., or Komipo, said Monday it struck a $3.4 billion deal with Switzerland's Vitol SA to buy liquefied natural gas for 10 years starting in 2015.

Komipo, the power-generating unit of Korea Electric Power Corp., plans to take in 400,000 metric tons of LNG a year from Vitol from 2015 to 2024, the company said in a statement.

The contracted annual import is equivalent to 17 percent of Komipo's consumption in 2011 for its power generation. The thermal power generator also has an option to purchase more than the initially contracted volume, depending on global prices.

The imported liquefied natural gas will replace the gas Komipo formerly bought from state-run Korea Gas Corp., the world's largest corporate buyer of LNG, the statement added.

The company didn't disclose price details but said the deal was signed at a relatively competitive price compared with recent long-term deals signed with other Asian countries.

The deal volume is quite small, compared with what had been expected, Woori Investment & Securities analyst Chang Lee told the Wall Street Journal.

Similar deals from South Korean companies are likely to happen slowly, over a long period, while the impact of the deal on Komipo's earnings will depend on how much cheaper the LNG is in comparison with Kogas prices, Lee said, according to the Wall Street Journal.

Komipo owns and operates various power plants from steam power plants, internal combustion and combined cycle thermal power generation plants to the pumped-storage power plants and renewable energy facilities.

Shares of Korea Electric Power Corp. (NYSE: KEP) rose 15 cents, or about 1.6 percent, to $9.78 a share.