That is what J. Basterra, using data from the UN, Tax Justice and ATTAC, denounces at Basque daily Gara today. The never collected tax revenue (250 billion euros yearly) could fully finace the UN project to reduce poverty by half globally for 2015 (goal that, of course, will not be achieved, not even approached). European nations and EU itself, among others, are full accomplices of these financial pirate heavens, some of which are either autonomous colonies of EU states (case of Cayman Islands, for example) or tightly associated with EU (Switzerland, Liechtenstein, Andorra, Monaco).
What this highlights anyhow is how Capitalism itself has gone global and beyond the surveyance and regulator activity of sovereign states and international organizations. These tax heavens are certainly unfair competitors of EU states and companies without transnational status and are damaging European (as well as others') economy. This is something I already read about in the mid-80s: that states can hardly anymore regulate global Capitalism and that, in case of crisis like the one we are suffering now, the separate or even coordinated efforts of these states will hardly serve for anything, as a large fraction of capital (the most central, strategic and elusive fraction of it) is well beyond their reach.
The crisis is probably unmanageable in such circumstances.