The German Federal Intelligence Service paid an informant some 5 million euros for a list with the names of account holders from a Liechtenstein Bank. German investigations thereupon revealed a massive tax evasion scandal! Hundreds of people in Germany are suspected of having stashed away millions of euro in Liechtenstein to escape taxes in Germany.
The tiny Alpine principality of Liechtenstein, a major European tax haven, accused the Germans of attacking its sovereignty and of breaking the law by buying secret (stolen) data and sending in spies to uncover the scandal.
The OECD in Paris criticized the Liechtenstein practice of allowing foreigners to open trusts there anonymously by registering them through a local attorney or trustee.
The policy of "excessive" secrecy of banks in Liechtenstein might have attracted many rich people and more countries are interested in the data bought by the German intelligence agents.
Interestingly a lot of literature on Liechtenstein is about financial matters, trusts, anti-money laundering issues and the transparency of its fiscal regime. Read more on Liechtenstein and its special place in Europe.