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.

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.

Swiss bank UBS is working with an independent ombudsman to shed light on Nazi-linked accounts, it said on Saturday, after the Wall Street Journal newspaper reported some accounts at collapsed bank Credit Suisse,

The U.S. Wall Street Journal (WSJ) reported that customer information of those involved, which had not been disclosed, was found in an investigation into