California doctor Howard Kornfeld, described in the report as a national authority on opioid addiction treatment, he was contacted by Prince's representatives on April 20 because the musician "was dealing with a grave medical emergency," the Star Tribune reported, citing William Mauzy, a Minneapolis attorney it said was working with the Kornfeld family.

Kornfeld, who runs Recovery Without Walls, an outpatient clinic in Mill Valley, California, was unable to meet with Prince the next day, when Prince was found dead at age 57 at his home-studio complex called Paisley Park in a Minneapolis suburb, the paper said. Kornfeld had planned to fly out the following day, the publication revealed.

Neither the doctor nor the lawyer responded to Reuters requests for confirmation of the report.

The hope was that Prince would agree to go to California for care, which would include around-the-clock nursing support, the paper said.

Prince's cause of death remains undetermined and it could be weeks before results are released from an autopsy. Prescription opioid medication was found on him, media reported, citing law enforcement sources. Police have said they found no signs of suicide or obvious trauma in Prince's death.