A state-run research institute has assessed that there is inadequate competition within the domestic telecommunications market.

A report by the Korea Information Society Development Institute said on Monday that as of 2020, the nation's largest service provider SK telecom had a 47-point-seven-percent subscriber share and a 47-percent share of retail sales.

The figures are four-point-six percentage points and three-point-five percentage points, respectively, higher than OECD averages among leading telecommunications companies in member states. The difference further widened compared to 2019.

The subscriber share gap between the largest and the second-largest service provider expanded one-point-eight percentage points on-year to 19-point-three percentage points, higher than the OECD average of 12-point-two percentage points.

According to a study by Japan's Ministry of Internal Affairs and Communications, users in Seoul were subject to the second- or third-highest telecommunications service fees among six major cities around the world in 2020. The highest service fees were found to be in New York City.