LONDON -(MarketWatch)- Governments in a number of developed economies should consider introducing or raising taxes on wealth and property as part of a range of measures designed to halt and reverse rising income inequality, the Organization for Economic Cooperation and Development said Monday.

In its first report on the subject since 2008, the OECD said the gap between rich and poor in most of its 34 members has continued to widen. The average income of the richest 10% of the population in developed economies is now nine times that of the poorest 10%, having been five times as large in the 1980s.

Since the mid-1990s, differences in income have risen rapidly even in countries such as Sweden and Germany that have traditionally had the least inequality. Only two OECD members--Mexico and Chile--have managed to buck the broader trend, but that was from the starting point of having the most unequal income distributions.

The OECD said that rising inequality was fueling dissatisfaction with social and economic structures in a number of developed economies.

"The social compact is starting to unravel in many countries," said Angel Gurria, the OECD's secretary general. "Young people who see no future for themselves feel increasingly disenfranchised. They have now been joined by protesters who believe that they are bearing the brunt of a crisis for which they have no responsibility, while people on high incomes appear to have been spared."

The OECD said a number of factors have contributed to the rise in inequality. Technological change has been disproportionately beneficial to the highly skilled, as have changes in labor market and other regulations designed to respond to the increase in competition during a period of rapid globalization. Reductions in tax rates for those on high incomes, and reductions in welfare benefits for those without work or in low paid employment has also played a part, the OECD said.

"This study dispels the assumptions that the benefits of economic growth will automatically trickle down to the disadvantaged and that greater inequality fosters greater social mobility," Gurria said. "Without a comprehensive strategy for inclusive growth, inequality will continue to rise."

The OECD said that strategy should include better education systems and more training when people start work, while providing freely accessible education and health services would also help.

But the Paris-based think tank said governments should also review their tax systems to ensure that higher earners pay their "fair share" of taxes.

"This can be achieved by raising marginal tax rates on the rich but also improving tax compliance eliminating tax deductions, and reassessing the role of taxes in all forms of property and wealth," the OECD said.

The OECD said income inequality was generally high in English-speaking countries, with both the U.S. and the U.K. in a group of countries where the incomes of the richest 10% were 15 times greater than those of the poorest 10%.

That ratio averages five to one in a number of northern European countries, including Denmark, Norway, Finland and Sweden.

The OECD study only covers the period up to 2007, but its authors said that levels of inequality are unlikely to have changed during and immediately after the financial crisis.

"My guess is there will not be a lot of change," said Michael Forster, the study's lead author. "There has been an enormous increase in unemployment, but at least temporarily some of the top incomes have fallen as income from capital has gone down."