The divide between the wages of the rich and the poor is growing in nearly all of the world's leading economies, according to think tank the OECD.
Researchers examined 22 countries and found that inequality grew in 17 of them between the 1980s and the financial crisis of 2008.
Chile, Mexico, Turkey and the United States were the most unequal nations.
Inequality rose fastest in the the UK - it peaked in 2000, then fell, but is now rising again.
Even traditionally egalitarian countries such as Germany, Denmark and Sweden have experienced a growing wealth gap in recent decades.
The OECD found that globally, the richest 10% of the population earns nine times more than the poorest 10%.
'No trickle down'
In the UK, the richest 1% has seen their incomes double since the 1970s.
The average annual income for the richest 10% of working age British people in 2008 was £55,000 - which is 12 times higher than the average for the bottom 10%.
The report says that the ratio of the richest 10% of the overall population to the poorest 10% in the UK is 10 to one - slightly higher than the OECD average.
Launching the report in Paris, OECD secretary-general Angel Gurria said: "This study dispels the assumptions that the benefits of economic growth will automatically trickle down to the disadvantaged and that great inequality fosters social mobility.
"Without a comprehensive strategy for inclusive growth, inequality will continue to rise."
The OECD say that changes in the labour market over the last 30 years are to blame.
They claim that technology has benefited the highest paid while poorer workers have been forced to take jobs that are temporary, part-time or badly paid. Self-employed workers also tend to earn less.
Similar trends were observed in periods of growth and during recessions.
The organisation recommends that governments around the world invest to create better quality jobs and to improve the skills of workers.
Mr Gurria said: "Our report clearly indicates that upskilling of the workforce is by far the most powerful instrument to counter rising inequality."