The government wants to ask the UN Commission on the Limits of the Continental Shelf to recognize Korea's scientific and technical rights over a massive continental shelf south of Jeju Island.

The letter to the commission, to be sent later this month, is part of the government's efforts to claim sovereignty over the 19,000 sq. km continental shelf that stretches for 200 nautical miles to Okinawa.

"The Korean government's position is that the continental shelf is a natural extension of the peninsula," a high-ranking diplomatic source in Seoul said Wednesday. "Korea will soon submit geological, scientific and legal data proving this to the CLCS."

The maritime area covered by the shelf is under joint development by Korea and Japan under a 1974 agreement and is equivalent to 20 percent of Korea's land mass. The government began researching the area in 1999 and in 2009 submitted preliminary data to the CLCS.