Middle-class Americans have lost their status as the most prosperous in the world, a survey has found.

A person on the median income in the United States is now less well off than one in Canada.

The survey, published by the New York Times, shows median incomes - the middle 10 per cent of earners - are falling in the US compared with international competitors.

The disparity is explained by the fact that the richest 5 per cent of Americans remain by far the most affluent in the world.


But the poorest 5 per cent are worse off in the US than in other countries, including Canada, Sweden, Norway, Finland and Holland, all of which were behind America in poverty terms in the 1980s.

The gap between top, middle and lower income earners in the US is growing, according to the survey figures, compiled by the Luxembourg Income Study Database.

Although the US remains the world's richest country in terms of gross domestic product per capita, wealth distribution is concentrated at the top and middle-class incomes are rising far more slowly than those in the top 5 per cent.

An American family of four on a median income now takes home about US$75,000 ($87,005) after taxes - up 20 per cent since 1980 but virtually unchanged since 2000 after adjusting for inflation.

In Britain - as in Canada - middle-class incomes rose by 20 per cent between 2000 and 2010. Pay in this income bracket has risen more quickly in much of Europe than in the US, meaning other countries may also soon catch up with America.