The "global super-rich elite" are hiding at least an estimated $21 trillion (that's trillion, with a "tr") in tax havens like the Cayman Islands, according to a new study. That's a lot of money. Seriously: it's more than the U.S. and Japanese economies combined.

The study, 'The Price of Offshore Revisited', was written for the Tax Justice Network - an organization that campaigns against tax havens - by James Henry, a former chief economist at the consultancy McKinsey. Henry used data from the Bank of International Settlements, International Monetary Fund, World Bank and national governments to create the report, which also found that less than 100,000 people worldwide own about $9.8 trillion of the wealth held offshore.

Not everyone is convinced that the report's findings are accurate. John Whiting, a tax expert and UK government adviser, said "I cannot disprove the figures at all, but they do seem staggering. If the suggestion is that such amounts are actively hidden and never accessed, that seems odd - not least in terms of what the tax authorities are doing. In fact, the US, UK and German authorities are doing a lot". Whiting does concede that "there clearly are some significant amounts hidden away", but asks "if it really is this size what is being done with it all?"

If the figures are correct, Mr. Henry says "the lost tax revenues implied by our estimates is huge. It is large enough to make a significant difference to the finances of many countries". He also suggests that the discovery of this hidden cash is good news in one sense: "The world has just located a huge pile of financial wealth that might be called upon to contribute to the solution of our most pressing global problems".

The $21 trillion figure only covers cash holdings, and does not include possessions like real estate, gold, yachts and racehorses.

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