A former employee accused Wells Fargo & Co of instructing workers at a call center to refrain from telling customers about lost deeds or other missing documents, and of firing the worker who called the policy unethical, according to a lawsuit made public this week.

Duke Tran, who was a customer service specialist at the bank, says that his supervisor berated him for telling a husband and wife that their loan contract was missing from an internal system.

Tran and others later received an email instructing them not to tell customers about situations “where we have a lost contract, deed, any type of document, really, but especially when it relates to securing a property,” according to a copy of the email filed with the lawsuit.

The email told the employees “to say that we need to do further research or something similar” and then to escalate the phone call to…