Angel Gurria, secretary-general for the Organization for Economic Co-operation and Development, said the division between the haves and have-nots "polarizes societies."

"Growing inequality is divisive," Gurria warned in a statement while releasing the group's report in Paris.

The report, which encompasses 30 developed economies in Europe, Asia, the Americans and Australia, said that those in retirement years have made economic gains in the past 20 years. "In contrast, child poverty has increased," the report said.

"Children and young adults are now 25 percent more likely to be poor than the population as a whole," the report said. Single-parent households are three times more likely to be impoverished than the average household, in spite of OECD countries spending three times as much on family programs than they did 20 years ago, the report said.