Warren Buffett, the world’s most famous professional investor has slammed US Congress for allowing him to pay a lower tax rate than his secretary and his cleaning lady.

Speaking at a $4,600-a-seat fundraiser in New York for Democrat Senator Hillary Clinton, Mr Buffett, who is worth an estimated $52 billion, told the wealthy audience: “The 400 of us [here] pay a lower part of our income in taxes than our receptionists do, or our cleaning ladies for that matter."

"If you’re in the luckiest 1 per cent of humanity, you owe it to the rest of humanity to think about the other 99 per cent."

The comments of the world’s third richest man are among the most signficant yet in a debate raging on both sides of the Atlantic about growing income inequality and how the super-wealthy are taxed.

They echo comments made earlier this month by Nicholas Ferguson, one of the leading figures in Britain’s private equity industry, when he criticised tax rates that left its multi-millionaire venture capitalists "paying less tax than a cleaning lady".

Mr Ferguson, a 25-year veteran of the industry and now the chairman of SVG Capital, the biggest investor in Permira, was criticising "taper relief" rules which allow the tax private equity executives pay on their share of the investment profits to be reduced from the top capital gains rate of 40 per cent to 10 per cent.

Private equity and hedge fund investment staff are also the focus of proposed new legislation in the US. Last week, senior members of the Senate proposed to increase the rate of tax they pay on their share of the profits, known as carried interest, from the 15 per cent capital gains rate to about 35 per cent.

Mr Buffett told his audience, which included John Mack, chairman of Morgan Stanley, and Alan Patricof, founder of the US branch of Apax Partners, that US government policy had accentuated the disparity of wealth which hurt the economy by stifling opportunity and motivation.

Mr Buffett said he was taxed at 17.7 per cent on the $46 million he made in 2006, without trying to avoid paying higher taxes, while his secretary, who earned $60,000, was taxed at 30 per cent.

Mr Buffett, who runs Berkshire Hathaway and is generally regarded as the world’s most successful investor, said he was a Democrat because Republicans are more likely to think: "I’m making $80 million a year, God must have intended me to have a lower tax rate."

He said that a Republican proposal to eliminate elements of inheritance tax, which raises about $30 billion a year from the assets of about 12,000 rich families, would increase the disparity between rich and poor. He added the Republicans would seek to recover lost revenue by increasing taxes for the less well off.

"You could take that $30 billion and give $1,000 to 30 million poor families, or should you favour the 12,000 estates and make 30 million family pay an extra $1,000?," he said.

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