“We have found 450 legal and natural persons with a link to offshore structures and Switzerland,” Joel Weibel, spokesman for the Federal Tax Administration told SRF radio.
It is not clear whether any tax evasion has taken place.
Weibel said the data would now be passed to the cantons affected for them to check the names against the corresponding tax files and see whether tax evasion had occurred.
In April media groups began revealing the results of a year-long investigation into 11.5 million documents from the Panamanian law firm Mossack Fonseca, which specializes in creating offshore shell companies.
The documents revealed the names of leaders, politicians, celebrities and wealthy individuals from around the world who used the Panama-based firm to create offshore entities to hide their assets.
Major international banks, including Credit Suisse, were also named in the leak among those that requested the most offshore companies for clients.
According to the papers, Credit Suisse created 1,105 offshore companies and UBS 1,100.
Though offshore companies are not in themselves illegal, they can be used to engage in illegal activities such as tax evasion or money laundering.