Vadim Benyatov, who is the current head of Credit Suisse's central and eastern European division, was detained by Romanian prosecutors yesterday as part of an investigation in to the sale of government assets.
Prosecutors said that Mr Benyatov was being investigated along with several others on charges of commercial espionage linked to the case.
The men are being accused of obtaining confidential documents relating to the sale of the Romanian assets, and passing them on to private companies.
Credit Suisse has been invited to meet with prosecutors in Bucharest in order to discuss the situation.
The case will come as an embarrassment to Romanian authorities, who have promised to clamp down on corruption within the country's financial sector prior to it joining the European Union - due to happen in the new year.