Korea Gas, the world's biggest buyer of liquefied natural gas, may build an undersea pipeline to import the fuel from Russia if a plan to lay an overland link via North Korea falls through, CEO Choo Kang-soo said.

The utility discussed the possibility last week with Gazprom, Choo was quoted by his spokesman Lee Sang Wook as saying Wednesday.

Korea Gas signed an accord with Gazprom in September to import 7.5 million tons of gas. The attempt to get the North's consent to build a pipeline in its territory comes as ties between the two countries grow chilly after South Korean President Lee Myung-bak, who took office in February, vowed to take a tougher line on its neighbor than his predecessors.

A pipeline via North Korea is expected to be more economical although an undersea link from Vladivostok to Samcheok on South Korea's eastern coast is a possible route, Lee quoted Choo as telling reporters in Seoul.