SEOUL, Dec. 8 (Yonhap) -- Income inequality among elderly citizens in South Korea is the third highest in major economies, data showed Thursday, indicating that the country's public pension system remains relatively insufficient to support retirees.

The Gini coefficient for those aged 65 and older here stands at 0.409, the third highest among the members of the Organization for Economic Cooperation and Development (OECD), according to the OECD data.

A reading of zero means complete income equality, while higher numbers nearing one indicate a widening gap in earnings between rich and poor. The OECD data reflect after-tax income.

Mexico topped the group with the highest coefficient figure of 0.524, followed by Chile with 0.474, the data showed.

The Czech Republic had the lowest income gap among its elderly citizens, at 0.188. For the U.S., Japan, France and Germany, the Gini coefficients were 0.386, 0.348, 0.291, and 0.284, respectively.

The relatively wider income inequality in South Korea can be attributed in part to its insufficient public pension system compared with those of other advanced countries, experts said.