Swiss bankers sought to cover up the extent to which they helped the Nazis store looted assets during World War II by placing their account information under a secret file with the stamp “American blacklist,

A cache of client files stamped “American blacklist,” a designation for those financing or trading with Nazis or Axis partners, was recently found by investigators probing Credit Suisse, one of Switzerland’s biggest banks and now part of UBS.

The Swiss bank engaged in a “pattern of obstruction” by not sharing some information during past investigations into the lender’s ties to Nazis, the Senate Budget Committee said.