The latest court indictment alleged that the private banks were involved in opening accounts for UBS clients even after business termination in 2008, reported Financial Times.
The documents suggested that private banks had opened secret offshore accounts and provided client advice on contrary to US Securities and Exchange Commission regulations.
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In 2009, UBS had paid $780m in a deferred prosecution agreement with US in August 2009 and agreed to provide further client names if shown that other banks dealt similar to UBS.
Last month US probe agencies have also launched an investigation into Credit Suisse as part of a broader probe into Swiss banks suspected of helping Americans evade taxes.
