Investigators have launched a search of British banking giant HSBC's Geneva offices as part of a money laundering probe.
It follows allegations the bank helped clients evade millions of euro in taxes, Swiss prosecutors said.
"Following the recent revelations related to the HSBC Private Bank (Switzerland), the public prosecutor announces the opening of a criminal procedure against the bank... for aggravated money laundering," Swiss prosecutors said in a statement.
The prosecutors said they had opened the probe against the bank itself, but that "depending on the evolution, the investigation might be broadened to include physical persons suspected of committing or participating in acts of money laundering."
The announcement came just over a week after HSBC Switzerland found itself at the centre of a massive global scandal following the publication of secret documents.
The cache of files, made public in the so-called SwissLeaks case, claimed HSBC's Swiss private banking arm helped clients in more than 200 countries evade taxes on accounts containing €104 billion.
The files, which include the names of celebrities, alleged arms dealers and politicians, were originally stolen by former HSBC IT worker Herve Falciani in 2007.
According to the documents, billions of euro transited through the bank as customers from around the world tried to dodge tax commitments in their home countries or in a bid to launder proceeds through shell corporations.