US authorities are investigating whether banking giant Credit Suisse helped US citizens evade paying taxes.
The Swiss bank said said it had been notified that it was a "target" for investigation, but argued that this was part of a "broader industry inquiry".
Credit Suisse said it would cooperate with the investigation "subject to Swiss legal obligations".
In February the US indicted four Credit Suisse bankers for helping taxpayers hide money in secret bank accounts.
At the time, Credit Suisse had said that it was not part of the investigation.
In recent years US authorities have pressured several global banks to help them fight tax evasion.
The US Department of Justice's primary target was another Swiss bank, UBS.
It threatened the Swiss bank with legal action if it failed to hand over the details of 4,450 US customers suspected of tax dodging.
Following years of intense pressure from the United States, in June last year the Swiss parliament passed legislation permitting the country's banks to share customer details with US tax authorities.
UBS ended up paying a $780m fine, but more importantly the new legislation put an end to Switzerland's famed banking secrecy.
Earlier this year, US authorities said they were investigating the role of UK bank HSBC in helping Indian citizens living in the United States to evade taxes.