"It is possible we may set negative rates for franc accounts held by private customers, but they haven't been introduced yet, and they are not planned,” a spokesperson for the bank was quoted as saying by the WSJ. WealthBriefing contacted the bank but did not receive a response confirming the comment at the time of going to press.

The possibility of introducing negative rates "may be possible under certain market conditions", the ZKB spokesman told the WSJ.

Already, UBS and Credit Suisse in December have moved to charge fees on certain deposit accounts to discourage bank clients from parking cash as the Swiss economy struggles to cope with the strong investor demand for the franc, the report said.

In September 2011, the Swiss national bank capped the Swiss franc’s rate against the euro at SFr1.20 to protect the Alpine state’s exporters. Interest rates in the country are near zero and this fact has played a part in hitting the margins of Swiss banks.

The report added that Swiss banks have benefited from safe-haven inflows from investors fleeing the debt-ridden eurozone in recent months. Ironically, such inflows come at a time when Switzerland’s banks are seen as losing ground to firms in rival jurisdictions due to the international assault on the country’s bank secrecy laws.