Israel's finance ministry has asked for help from the Swiss authorities in identifying Israelis with undeclared assets at Union Bancaire Privée (UBP) and Bank Julius Baer.
The Swiss tax office is currently seeking contact information for account holders and giving the banks 20 days to provide the data. It will then decide whether it can provide assistance to Israel.
Thousands of Israelis have disclosed foreign accounts containing billions of dollars under a government amnesty program in recent years, as they sought to avoid prosecution in a crackdown on unreported capital.
The Geneva-based Union Bancaire Privée (UBP) said it is cooperating with the Swiss Federal Tax Administration, Reuters reported on Wednesday. The other bank targeted, Julius Baer, did not comment.
According to documents published in the Swiss Federal Register , the Israeli finance ministry is attempting to identify citizens who held accounts at UBP between 2014 and 2017 and who did not show they had fully met their tax obligations.
Reuters reported that a similar document showing Israeli interest in accounts at Julius Baer was made public earlier this month.
The Federal Register documents show that in both instances the private banks asked account holders with an Israeli address to document their tax compliance. Those who did not show sufficient evidence were told their business relationship with the bank would be terminated.
Switzerland has signed agreements with a number of countries, including Israel, for the automatic exchange of banking information following international pressure to crack down on offshore assets. The agreements mean that Swiss banks must share details on foreign clients with the tax office, which then passes the data on to these partner states.
Switzerland's highest court is still to decide on France's demand for UBS, the largest Swiss bank and the world's largest wealth manager, to hand over sensitive customer data, or whether to dismiss the request as a "fishing expedition".