Marcel Bruehwiler, chief executive of UBS Belgium unit, has been detained by local police on suspicion that he and the firm helped wealthy clients evade billions of euros in taxes.
Bruehwiler was charged with criminal organization, money laundering, illegal practice of the profession of financial intermediary and serious organized fiscal fraud.
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According to prosecutors, Belgian police carried out raids on at the bank and at the homes of a client and of Bruehwiler.
The information leading to the raid came from compliance officers who had left UBS or had been fired and no longer supported the bank’s tactics.
Bruehwiler, who was released after several hours of questioning, denied the charges, prosecutors said.
UBS said in a statement that it fully respected the law and would tolerate "no activity meant to allow any client to get around their tax obligations."
"UBS is cooperating fully with the Belgian authorities," it added.
