Montreal police are worried that a dangerous drug known as "purple heroin" has made its way into the city.

An internal note obtained by The Canadian Press says the police service's analysis and intelligence department has been informed of the drug's presence in the greater Montreal area.

The Ontario Provincial Police warned earlier this year about the dangers of the drug, which is also known as "purp" or "purple," and is typically made up of heroin, OxyContin and fentanyl or carfentanil.

Montreal police declined an interview request but said they were aware of the drug and were being vigilant.

Both Montreal and Quebec provincial police say the drug has yet to be seized during an arrest and no overdoses have yet been linked to it, while adding that police are not always informed of what substances a drug user consumed.

A spokesman for community service organization CACTUS Montreal says he's not surprised by the drug's presence, adding the best way to keep people safe is to provide opportunities for drug users to test their drugs before consuming them.