UBS AG Wednesday confirmed one of its highest-ranking executives has been indicted in the US in connection with a probe into alleged tax evasion, the latest blow for the Zurich-based bank which is struggling to put over $46 billion in mortgage write-downs behind it.

UBS said Swiss-born Raoul Weil, head of its sprawling private bank, will step down from his duties while he prepares to fight an indictment by a US Federal grand jury. "Mr. Weil denies any suggestion that he was aware of, engaged in or tolerated any illegal conduct in the operation of UBS's US-cross-border business," Aaron Marcu, an attorney for Weil, said in a statement.