WINNIPEG -- The College of Registered Nurses of Manitoba is warning its members of a 'serious scam' involving prescribed narcotics.

In an internal email to members obtained by CTV News, the college's CEO Katherine Stansfield said an elderly patient had been prescribed and dispensed a 'significant' amount of narcotics. The email said the next day, a person came to the patient's residence and said they were acting on behalf of the College of Physician and Surgeons of Manitoba (CPSM).

According to the email, this person provided an identification card and bag with the CPSM logo. They told the patient the prescription was incorrect and demanded they hand over all the drugs, which the patient did, the email said.

The person then placed the drugs into a lockbox and left.

"CPSM had no knowledge of this, has not authorized this individual or practice, and does not operate its investigations in this manner," Stansfield said in the email, adding the police have been informed.

"These narcotics have a high street value and are dangerous."

The college is asking all registered nurses and nurse practitioners to advise their patients of this scam when prescribing narcotics, and warn them not to hand over their drugs to any person claiming to be from CPSM or other organizations.

The email does not specify when or where this incident took place. CPSM told CTV News it advised its members of the incident on Monday.

CTV News has reached out to CPSM for additional comment.