An investigation is under way following suspected fentanyl-related overdoses at Westgate prison this year.

Lieutenant-Colonel Edward Lamb, Commissioner of Corrections, confirmed an internal investigation was ongoing.

The investigation follows a media report in April that multiple inmates at Westgate Correctional Facility had suffered overdoses thought to be connected with the drug.

The drug — a synthetic opioid 50 to 100 times stronger than morphine — is often cut with heroin and can be fatal even in extremely small doses.

Its arrival on the island has prompted warnings from health, law enforcement and government representatives.

The Bermuda Hospitals Board confirmed that two “highly suspect” overdoses thought to be linked to the drug had been treated within a week at the time of the media report.

Approached for an update, a spokeswoman with the Ministry of Health and Seniors said: “The ministry can confirm there have been four samples that have tested positive for fentanyl.”

The samples, she said, were collected between December 2016 and May 2017. No further information was provided.

No deaths due to fentanyl-related overdoses have occurred.