Up to $8 trillion now passes through offshore jurisdictions, according to a recent report in the International Herald Tribune.

No-one knows how much of this is illicit, because secrecy laws in many of these jurisdictions make it a crime to ask. For example, the government web site of the tiny Caribbean island of Antigua tries to attract offshore investors by bragging that it is bucking the trend "toward greater disclosure" of financial information. "The emphasis on nondisclosure provides a high comfort level," it says. Anguilla's web site says companies can incorporate there in just 24 hours, while Dominica boasts of the "absence of tax treaties or exchange agreements with any other country". The Cayman Islands has just 30,000 citizens, yet nearly 600 banks - making it the fifth-largest banking centre in the world. Bigger than Chicago, Rome, Frankfurt, Paris, Los Angeles and Dallas. Many of its banks exist simply on paper. One senior US official has said that some of these small countries, which offer both strict banking secrecy and an easy change of identities, are creating "one-stop shopping" for criminals.