MONACO (Yonhap) -- A key global chart showing oceanic boundaries and names all over the world has not demarcated the boundary of the waters separating the Korean Peninsula and Japan, a Korean professor said Wednesday, claiming the current sea map with the flaw is invalid as a basis for nautical charts.

Kim Shin, a professor at Seoul-based Kyung Hee University and head of the East Sea Forum, made the claim in Monaco as South Korean delegates have intensified diplomatic efforts for the International Hydrographic Organization (IHO) to concurrently use the name "East Sea" alongside the current "Sea of Japan" appellation.

The five-day IHO meeting from Monday is aimed at revising the global chart, titled "Limits of Oceans and Seas" and better known as S-23, including the water expanse presently referred to as the Sea of Japan. Seoul wants the chart revised to include the name East Sea as well.

"A flaw has been found that the current edition of S-23 does not demarcate a boundary of the East Sea, which is currently referred to as the Sea of Japan," Kim told reporters.

"Because a boundary is nonexistent, the single reference of the Sea of Japan in the current edition is fundamentally invalid," Kim said.

Seoul sent a 16-member delegation to the quinquennial IHO meeting but the delegates have said it is difficult to predict the outcome of the meeting.

Since the last conference in 2007, South Korea has revved up its diplomatic campaign to press the IHO to concurrently use East Sea and Sea of Japan to refer to the sea at this week's meeting aimed at revising the third edition of S-23.

The naming issue is particularly sensitive for Seoul as Tokyo has continually stepped up efforts to claim the South Korean islets of Dokdo in the East Sea. South Korea keeps a small police detachment on the volcanic outcroppings.

Korea has long campaigned for the adoption of its favored name for the waters that are widely termed the Sea of Japan, after Japan registered that as the official name with the IHO in the early 1920s, when Korea was under Japan's colonial rule.

The IHO published its first oceanographic chart for the region in 1929 and has since updated it three times, but each time, the body of water has been marked as the Sea of Japan.

Korean historians and experts believe the sea's original name was the East Sea, but that the term Sea of Japan became more widely adopted because Korea failed to properly counter Japan's campaign to change the name due to Korea's colonization by Japan and the 1950-53 Korean War