Income inequality, as measured by pre-tax household income across individuals within a country, declined in most Western countries from the end of the 19th century until about 1970, when it began to rise.
"The enormous increase of income inequality on a global scale is one of the most significant – and worrying – features of the development of the world economy in the past 200 years," said the report's authors.
Read MoreRich and poor alike are worried about income gap
Starting from the 1980s, most countries experienced a rise in their inequality levels, according to the OECD.
One of the most striking increases was in China, whose Gini coefficient—a measure of income distribution—rose by about half between 1980 and 2000.
An exception to the rule was Japan, which has maintained low inequality levels from the 1950s onwards, and South Africa.
In 2013, CEOs at major U.S. companies earned an average of 296 times their typical worker's salary, according to research from the Economic Policy Institute published in June 2014.
This September, a CNBC/Burson-Marsteller survey of 25,000 people across the world found that 76 percent of respondents thought the gap between CEO and average worker salaries was growing.
Read MoreDo companies pay 'fair share'? Depends whom you ask
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