Officials looking into the death of Prince are investigating whether he died from an overdose and whether a doctor was prescribing him drugs in the weeks before he died.

Among other things, they are looking at whether a doctor was with the music legend on a plane that made an emergency landing less than a week before he died, according to a law enforcement official.

The official said investigators are also looking into what kind of drugs were on the plane and at Prince's house in suburban Minneapolis.

He said paramedics gave Prince a shot of Narcan after his plane made the emergency landing, which is used in suspected opioid overdoses.

The official spoke was speaking to Associated Press on condition of anonymity.

Prince died on April 21 after collapsing in a lift at his Paisley Park compound.

A coroner has said it could be weeks before the results of a post-mortem can be disclosed.