HSBC's Swiss arm was searched by prosecutors on Wednesday as part of a new money-laundering investigation, amid reports the bank helped clients dodge significant amounts of tax but hiding funds overseas.
Officials swarmed the Geneva-based premises after a money-laundering investigation was launched to survey any illegal activity operating form within the bank.
Prosecutors in Geneva revealed in a statement that they have opened an official investigation into suspected aggravated money-laundering against as yet unknown individuals and the subsidiary as a whole.
The statement also claimed that the investigation was based on "the recent published revelations" about HSBC.
The bank itself has so far declined to comment but its chief executive officer Franco Morra revealed last week that it had closed any accounts belonging to clients who "did not meet our high standards".
He also said that any revelations published about "historical business practices" were not reflective of current banking operations.