Le Matin said the same letters were sent to the Cantonal Bank of Geneva (BCGE), UBS, Credit Suisse and HSBC, targeting not just bankers but their “corrupt lawyers”.
The writer of the letter said that the financial institutions have assumed all the rights “above all those of corruption”.
According to Le Matin, the letter warns that “all those in charge will be punished, for example, by a capital punishment”.
This type of letter is not common, a spokesman from the BCGE is quoted as saying.
The bank has filed a complaint and an investigation is under way.
The letters were mailed from a post office on the Rue de Stand between February 23rd and 25th.