A Canadian bank cancelled accounts of customers of Iranian origin with no chance to deny they violated financial sanctions, customers have reported.
They allege that TD Bank gave little or no notice before telling customers to take their funds elsewhere.
Customers and supporters said they were targeted because of Iranian names.
TD Bank told the BBC it did not target people based on ethnicity or nationality, but it was required to comply with Canadian law on sanctions.
"This episode shocked us," said Pooya Sadeghi, a real estate agent whose father-in-law's account was closed.
He has created a Facebook page entitled "Condemn TD Bank in their Treatment of clients with Iranian Background" to draw attention to the issue.
"Never in our wildest dreams did we imagine that a major bank in Canada would treat us like we are second-class citizens and undeserving of answers."
Since 2010, the Canadian government has imposed a series of sanctions against Iran intended to pressure the Islamic republic to suspend nuclear enrichment activities and co-operate with the International Atomic Energy Agency.
As part of the sanctions, Canadian banks are forbidden to provide financial services "to, or for the benefit of Iran, or any person in Iran", TD wrote in a letter to an Iranian-Canadian customer.
More than a dozen Iranian-Canadian TD customers told the BBC their checking and savings accounts were closed, credit cards and lines were revoked, and mortgages not renewed.
"I felt like a second-class Canadian," said an Iranian woman in British Columbia who only found out her account had been closed when she entered a branch to withdraw cash.
"They were simply told to take their money elsewhere," said Kaveh Shahrooz, a lawyer and vice-president of advocacy group Iranian-Canadian Congress, which held an emergency meeting in Toronto last week to gather anecdotes and formulate a collective response.
"Many are pensioners or students who got small sums of money from Iran and many hadn't received any money from Iran at all," he said.
"It seems like the bank is being over-zealous. They see an Iranian name and they close their bank account."
A spokesman for TD Bank rejected suggestions it had specifically gone after Iranians, and said Canadian law required the bank to comply with banking laws and regulations and Canada's economic sanctions against Iran.
"We value all our customers regardless of their ethnicity or heritage - to suggest otherwise would simply be false," said spokesman Mohammed Nakhooda.
He said the bank had tried to contacted the customers whose accounts it closed.
"We understand that this is a sensitive issue and that is why we took additional measures to reach out to customers who would be impacted by the regulation," he said.
"In cases where we did not hear back from customers to confirm their information, we were required to apply the regulation."
But TD customers told the BBC they were not asked to account for any of their transactions before the closure of their accounts.
"I was never contacted by TD to talk about any of my bank account activity," said Farshid Ganj, who said he had been a TD customer for seven years.
"I went the extra mile to get an answer and after dozens of phone calls and branch visits I got the same response: 'We can't give you the details of why your account was closed'."
A spokesman for Foreign Affairs and International Trade Canada said banks are advised to apply the Iranian sanctions to individual accounts on a case-by-case basis.
The ministry also offers waivers for some non-commercial remittances of CAN$40,000 ($39,200; £25,200) or less from Iran to Canada.