“The bank will have to negotiate a DPA separately with the American authorities, which will also contain a fine,” a spokesperson was quoted telling Bloomberg.

The Swiss firm confirmed the story to this publication but did not elaborate on details.

ZKB may have to pay a fine of as much as SFr720 million to US authorities, the Swiss publication Tages-Anzeiger reported, but did not give a source for the information.

Switzerland has been in talks with the US to resolve a Justice Department investigation of at least 13 financial firms that allegedly helped US nationals hide money from the Internal Revenue Service. A number of large Swiss firms, such as UBS, Credit Suisse and Julius Baer, no longer provide offshore banking to US citizens.

One of the most dramatic developments has been the demise of the Wegelin & Co name – the oldest in Swiss banking . In January, Wegelin & Co pleaded guilty in New York City to conspiring to help conceal client money from the IRS. The non-US part of Wegelin has been transferred to Switzerland's Raiffeisen Group. In 2009, UBS settled criminal and civil charges of aiding tax dodgers by a large fine and transfer of some client account data, seen as a breach of Switzerland’s decades-old bank secrecy laws.

As previously reported in local Swiss media, Finance Minister Eveline Widmer-Schlumpf has said an agreement between Switzerland and the US was close to being completed.

In its annual report, Zürcher Kantonalbank reported that it “performed well over the 2012 financial year”. Operating income rose 1.2 per cent on the previous year, at SFr 2.1 billion, while group profit from operations was slightly below the figure for the previous year, at SFr744 million - prior to a non-recurring expense of CHF 150 million for the pension fund.