The Swiss Competition Commission has said that it has started a formal investigation on Monday against eight banks for possible manipulation of major currency rates.
The suspects include Swiss banks UBS and Credit Suisse as well as major foreign lenders.
“There is evidence that anti-competitive agreements were made between these banks to manipulate exchange rates in the currency market,” the commission said.
The market regulator had started preliminary investigations in September, and authorities in other countries including Britain, Hong Kong, and the United States have also been looking into the alleged rigging of the $5.3 trillion-a-day foreign exchange market.
The Swiss probe also affects British banks Barclays and Royal Bank of Scotland, US banks JP Morgan Chase and Citigroup, and Swiss banks Julius Baer and Zuercher Kantonalbank.