Raids on more than a dozen Credit Suisse bank branches in Germany will conclude on Friday, apart from in Frankfurt, where investigations will continue into next week.
Düsseldorf state prosecutor Johannes Mocken described the operation as “very successful”, saying “far more than 100 boxes” of files had been confiscated from 13 branches.
On Wednesday Credit Suisse offices were searched in Düsseldorf, Berlin, Munich and other German cities after the authorities paid for confidential banking data that had been stolen from Switzerland.
German tax investigators were seeking evidence against Credit Suisse employees as well as clients.
Mocken declined to give more details about the investigation, but he did say that Credit Suisse had been professional and cooperative.
"In the countries where it operates, Credit Suisse runs its business in line with the applicable rules and regulations," said Mocken.
Swiss banks have come under increasing pressure in the past 18 months from a number of countries that accuse Switzerland’s financial system of aiding and abetting foreign tax cheats.
swissinfo.ch and agencies