Their concern comes after it was revealed he did not visit the closest pharmacy to his house to obtain medication just hours before he died last month.

According to TMZ, the 57-year-old singer visited a Walgreens chain pharmacy nearly 10 kilometres away from his Paisley Park estate on April 21, the day he was found unresponsive and later declared dead.

Prince had visited various Walgreens outlets four times in the week before his death.

TMZ estimates there are eight other pharmacies between the singer's Minneapolis home and the pharmacy he visited on the day he died.

The tabloid news site said family members of the star were "worried the singer was using multiple doctors and aliases" so that the large number of prescription drugs he was obtaining would not raise any alarm.

Media outlets including CNN have reported that anonymous Minneapolis law officials informed them he had prescription opioid medication on him when his body was found.

However, no cause of death has been formally determined.

The Midwest Medical Examiner's Office, which released a statement on the day of Prince's death saying they had completed a full autopsy, said results of a toxicology scan could "likely take weeks".

In a press conference last week Carver County Sheriff Jim Olson ruled out suicide as a possible cause of death, adding that there were "no obvious signs of trauma" to the singer's body.

Fairfax Media