Swiss police are searching offices of the Geneva subsidiary of HSBC bank in an inquiry into alleged money-laundering.
Prosecutors said they are investigating HSBC Private Bank (Suisse) and persons unknown for suspected aggravated money laundering.
The investigation could be extended to people suspected of committing or participating in money laundering.
It follows the recent published revelations about the private bank
The bank's chief executive, Franco Morra, said last week it had shut down accounts from clients who "did not meet our high standards".
Morra added the revelations about "historical business practices" were a reminder that the old business model of Swiss private banking was no longer acceptable.
The police raid comes more than a week after allegations first emerged that HSBC's Swiss private bank may have helped wealthy clients evade tax.
HSBC published a full-page advert in several weekend papers containing an apology over the claims.
HM Revenue & Customs was given the leaked data in 2010 and has identified 1,100 people who had not paid their taxes.