Thousands of CIBC and Bank of Montreal customers have been issued new credit cards from their banks along with warnings their old cards may have been used fraudulently, CBC News has learned.

Neither bank is releasing details, but some of the customers told the CBC they were told that the cancellations were linked to a major security breach at Winners and HomeSense.

Shannon Kohlman was perplexed when she received a letter saying her credit card may have been used fraudulently: 'I didn't lose it anywhere. I didn't leave it.… Why am I at risk?'
(CBC)

In January, the U.S.-based parent company of Winners and HomeSense revealed that millions of credit card accounts may have been compromised after hackers stole customer information from its computer systems. TJX Cos. said the stolen information covered transactions from 2003 into 2006.

Winnipeg resident Shannon Kohlman told CBC News that she was perplexed when she received a strange letter from CIBC about her VISA card.

"Your account may be at risk of being used fraudulently without your authorization," it read. "In order to protect your account and to minimize this risk, we are issuing you a new card."

"That makes me suspicious of what's happening with my credit card," Kohlman said. "I didn't lose it anywhere. I didn't leave it. What's happened? Is it the internet? Why am I at risk?"

The letter didn't explain the problem, but a bank clerk later told her it had to do with the Winners and HomeSense breach.

In early February, a spokesman for Winners and Homesense said the hackers did not get information on Canadian debit card transactions.

Consumers' group calls for more accountability

Bruce Cran of the Consumers' Association of Canada said his organization has fielded around 1,000 complaints so far.

"It creates a great deal of anxiety and that's what we've been witnessing," Crane told CBC News Tuesday. "People phone us looking for assistance … we can't give them much comfort."

The banks wouldn't say how many customers have been affected, what the security breach was or whether any credit cards have actually been misused. They also wouldn't disclose why they have reissued cards when other banks have not.

"Security investigations are obviously highly confidential and our customers understand that," Bank of Montreal spokesman Michael Edmonds told CBC News.

"We're being extremely proactive in ensuring that we are monitoring their accounts and protecting their information."

The consumers' group is going before a parliamentary committee on Thursday to push for banks and other companies that lose people's personal information to be held more accountable to the public.