Swiss bank Credit Suisse says it is being investigated by the United States Department of Justice over former cross-border private banking services to US customers.

The bank said it received a letter notifying it that it was being probed by the DoJ on Thursday.

"Subject to our Swiss legal obligations, we will continue to cooperate with the US authorities in an effort to resolve these matters," Credit Suisse said in a statement released on Friday.

It added that it had been reported that the “US authorities are conducting a broader industry inquiry”.

Four bankers who were working or had worked at Credit Suisse were charged earlier this year with conspiring to help clients in the US to evade taxes, according to an indictment.

The US authorities have been stepping up their fight against offshore tax evasion and have had Swiss banks in their sights. In February 2009, other big Swiss bank UBS was charged with helping US citizens evade taxes. The bank avoided prosecution by paying $780 million (SFr636 million), admitting that it had fostered tax evasion and by agreeing to hand over data on more than 250 accounts.

The Swiss government later handed over data on an additional 4,450 UBS accounts to resolve a lawsuit.

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