Although Wegelin had no branches outside Switzerland, it accessed U.S. banking through a correspondent UBS account in Connecticut.

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Second, the nature of correspondent banking will change.

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Our correspondent says the main example is banking giant UBS, which wrote off billions in the wake of the 2007 sub-prime mortgage crisis, and then had to be bailed out by the Swiss government.

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But our correspondent said further direct government investment in the banks - a new banking bail out - seems less likely, although given the scale of the crisis this option has not been definitively ruled out.

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The Vatican Bank - known officially as the Institute for Works of Religion - has hitherto exempted itself from international banking regulations on the grounds that it is not a real bank in the normal sense of the word, our correspondent says.

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