Pills found at the home of deceased star Prince were mislabeled - when in reality they contained highly-powerful fentanyl - an official has revealed.

Autopsy results in June revealed the guitarist had died of an accidental overdose of the drug - a synthetic opioid 50 times more powerful than heroin.

However, according to an official investigating the musician's death, nearly two dozen pills found at his estate were falsely labeled as hydrocone, a weaker type of opioid.

According to records obtained, the 57-year-old also had no medication prescriptions from the state of Minnesota in the 12 months leading up to his death on 21 April.

Many of the pills seized from Prince's home were found to have other drugs in them, the official also revealed.

A number of these were found stashed inside bottles of aspirin and Vitamin C that had been tucked inside a suitcase and bags.

Authorities also discovered a prescription bottle in someone else's name containing 10 pills in Prince's possession

The official said Prince had many of these pills with him on 15 April when the plane he was on made an emergency stop in Moline, Illinois, after he fell ill from a suspected drug overdose as he was heading home from a performance in Atlanta.

Tests on Prince prior to his death did not show fentanyl in his system, meaning he wasn't a long-time abuser of that drug, but likely took the fatal dose sometime in the 24 hours before he died, according to the official.

In recent years, fentanyl has been responsible for a surge in overdose deaths in some parts of the US.