Police investigators on Montreal's South Shore are alerting residents to be wary of fake representatives of banks attempting to defraud victims.

The Longueuil police (SPAL) said there has been a recent increase in potential fraud cases involving "fake representatives."

"In the last few months, we have intervened in more than 50 such cases following complaints received from citizens," the SPAL said in a release.

The alleged scam involves suspects contacting residents at home by phone telling them about fraudulent transactions related to their bank accounts.

"The fraudsters use a web-based app that makes DESJARDINS appear on the target's caller ID," the SPAL said. "The suspect then tells the person that they are a victim of fraud and asks them to deposit their bank cards and personal identification numbers (PIN) in an envelope so that a colleague can go and retrieve them as quickly as possible."

The victim is told a new card will be delivered, and someone shows up to pick up the envelope, the SPAL said.

"This is usually done under pressure, claiming urgency, while the victim is sometimes still on the phone with the fake representative," police say. "Transactions are then made within minutes and hours at merchants located near the address where the cards were retrieved."

Police who investigate fraud are reminding citizens to not give away personal information (name, address, date of birth, social insurance number etc.) and that no bank will contact customers to retrieve debit or credit cards or PINs.

Those contacted by someone claiming to work for a bank are advised to call the bank back, using another phone if possible, using the number on a debit or credit card immediately.

The anti-fraud Canada website has more information on various types of fraud, and contact information to report suspicious activity.