The Swiss Banking Commission has opened an enquiry into the conduct of five banks with links to Peru's former intelligence head, Vladimiro Montesinos.
A spokesman named the banks as UBS, Credit Suisse subsidiary Bank Leu, two Israeli banks, Leumi and Fibi, and Crédit Agricole Indosuez.
The Swiss justice authorities have frozen a total of $70 million (SFr115.5 million) in 17 accounts held at the banks. They believe the accounts, opened in the names of people close to Montesinos, contain funds he misappropriated.
Speaking in November, when the first four accounts were frozen, the Zurich district prosecutor Cornelia Cove, said much of the money "very likely originates from payments of commissions connected to arms transactions between Russia and Peru".
Cove said Switzerland had requested more information from the Russian and Peruvian authorities.
In a report on Saturday, the "Tages Anzeiger" newspaper said Switzerland's biggest bank, UBS, was most closely implicated in the Montesinos money affair, having handled $40 million in suspect funds.
Peru is conducting its own investigation into corruption allegations against Montesinos, and has asked Switzerland for legal assistance.
Viewed as the power broker behind the deposed president, Alberto Fujimori, Montesinos is in hiding, having fled Peru last September.
swissinfo with agencies