Contrary to government assertions, income disparities are rising -- as is the relative poverty rate -- because the number of nonregular workers with low wages has increased since the prolonged slump in the 1990s, according to an expert on income.

"It's very obvious that the number of poor people is growing," Toshiaki Tachibanaki, a professor at Kyoto University's Graduate School of Economics and former president of the Japanese Economic Association, said in a recent presentation to the Foreign Press Center Japan in Tokyo.

The Cabinet Office earlier this year denied there has been a substantial increase in the income gap. The office said there has been little change in "middle-class" awareness among people in the past 10 years and the number who view themselves as being in the middle class are proportionately higher than people in the West.