The nation's top-10 percent rich have 45 percent of the national income, the largest gap in the Asia-Pacific region. Their income share is also growing rapidly, deepening the economic polarization, a report says.
According to the International Monetary Fund report, Koreans belonging to the top 10 percent in income took up 45 percent of the national income in 2013. The income share was highest in Asia and Oceania, followed by Japan (41 percent), New Zealand (32 percent), Australia (31 percent) and Malaysia (22 percent).
The income share of Korea's top-10 percent grew 16 percent from 29 percent in 1995. The comparable shares in other regional countries grew 1-2 percentage points on average, said the report on distribution of growth outcome and economic inequality in the Asia-Pacific region.
"The growth rate of income share of the top-10 percent income bracket in Korea is astonishingly high," it said. "As the result of recent research, the social mobility of Korean society has fallen because of rapid population aging, a wide wage gap between regular and non-regular workers and sexual discrimination at workplaces."
However, income equality as a whole has not changed much in Korea, however.
The nation's Gini coefficient -- the gauge of economic inequality ranging from 0 to 100 -- edged down from 32 in 1990 to 31 in 2013. Among the 22 countries analyzed, the Gini coefficient of 15 countries rose over the cited period. China's Gini coefficient, for instance, surged from 33 to 53, and that of India jumped from 45 to 51.
"To prevent the widening of inequality, the government needs to expand its social welfare spending and enhance the progressivity of taxes," the IMF report said. "It also should try to expand financial inclusiveness (by supporting the low-income class, which is alienated from financial services)."
Statistics Korea disputed the report.
"This is not the IMF's official report but a working paper, and the figures in this report are in the World Wealth and Income Database run by Thomas Piketty," the government's statistical agency said. "The sources of this data are not governmental statistical organs but individual researchers, made by different methods and lacking in unified standards, so they are not suitable for official comparison of countries."