Fundamental shortcomings in the nation's wealth redistribution policy suggest the have-nots are still being left behind, despite a new report showing little change to income inequality, according to one prominent economist.

A welfare ministry survey, released Thursday, concluded Japan's economic inequality "has not widened" as per a key gauge known as the Gini coefficient, which measures the concentration of income in a country.

The report showed the Gini index, in which a value indicates the level of inequality with 1 being highest, stood at 0.3759 in 2013 after income redistribution is taken into account, almost unchanged from 0.3791 in 2011, when the ministry last conducted such a survey.