The Swiss Competition Commission has launched an investigation into possible cartel behaviour by a dozen banks including UBS and Credit Suisse.
The commission said that the banks are suspected of colluding to influence key interest rates and the trading conditions for derivatives.
It says the probe covers Switzerland's two biggest banks.
Competition authorities in the United States and Britain have also begun investigations into whether banks misstated the London Interbank Offered Rate, or LIBOR, that underlies many commercial interest rates.
The commission said in a statement the probe relates to "specifically, collusion between derivative traders might have influenced the reference rates LIBOR and TIBOR".
The London Interbank Offered Rate, LIBOR, and the Tokyo Interbank Offered Rate, TIBOR, underlay many commercial interest rates.
The commission said the banks are also suspected of illegally influencing market conditions for derivatives based on these reference rates.
The foreign institutions named in the Swiss probe are: Bank of Tokyo-Mitsubishi UFJ, Citigroup, Deutsche Bank AG, HSBC Holdings, JP Morgan Chase, Mizuho Financial Group, Rabobank Groep N.V., Royal Bank of Scotland Group, Societe Generale SA and Sumitomo Mitsui Banking Corporation.