Prince's cousin has said the musician had decided not to use drugs and alcohol when he was young and appeared "perfectly healthy" before his unexpected death at the age of 57.

Questions have been raised following Prince's death about whether he was hiding serious health problems from his fans.

And there were also unconfirmed reports that he may have taken an overdose of the same painkiller used by Michael Jackson – although the authorities pointed out that medics who went to treat him had not used an overdose medicine.

Chazz Smith, Prince's cousin, said he could not comment on reports about Prince's health and would not say when he last saw the star.

"I can tell you this: what I know is that he was perfectly healthy," said Mr Smith, who formed a band with Prince when they were children.

He said Prince swore off drugs and alcohol as a kid, and the group they played with saw a lot of music greats fall, so "we decided to never get into that stuff, and no one did".

Prince cancelled a series of shows and was reportedly taken to hospital after an emergency plane landing in the weeks before his death.

A spokesman for the star said he had been suffering from flu after his jet made an emergency landing on the morning of 15 April.

The celebrated artist was scheduled to perform a series of surprise shows in St Louis earlier this week, but they were cancelled last week due to health concerns.

Prince - A Life in Pictures Show all 10 1 /10 Prince - A Life in Pictures Prince - A Life in Pictures Prince Rogers Nelson, known by his mononym Prince, who has died at the age of 57 at his Paisley Park compound in Minnesota PA Prince - A Life in Pictures Prince performs in concert at Riverfront Coliseum during his Purple Rain Tour in Cincinnati, Ohio, on January 22nd, 1985 AP Prince - A Life in Pictures US singer and musician Prince performing on stage at the Stade de France in Saint-Denis, outside Paris on June 30th 2011 AFP / Getty Prince - A Life in Pictures US musician Prince performing on the Stravinski Hall stage during the 47th Montreux Jazz Festival, in Montreux, Switzerland on 21 April, 2013 EPA Prince - A Life in Pictures Prince performs during the 'Pepsi Halftime Show' at Super Bowl XLI between the Indianapolis Colts and the Chicago Bears on February 4, 2007 2007 Getty Images Prince - A Life in Pictures Prince plays during a press conference at the Miami Beach Convention Center, February 1st, 2007 AP Prince - A Life in Pictures Prince performs during the second day of the Coachella Valley Music and Arts Festival in Indio, California on April 26th 2008 AP Prince - A Life in Pictures Prince performs before a sold-out audience, in Houston on January 11th 1985 AP Prince - A Life in Pictures Musician Prince gestures on stage during the Apollo Theatre's 75th anniversary gala in New York, June 8, 2009 Reuters Prince - A Life in Pictures Prince Rogers Nelson, known by his mononym Prince, who has died at the age of 57 at his Paisley Park compound in Minnesota PA

Prince was found in an unresponsive state late on Thursday morning in a lift on the first floor of his home.

Emergency service personnel performed CPR, but were unable to revive him.

"Yes, it's Prince," an unidentified male caller told emergency services, according to a transcript of the 911 call.

Prince was pronounced dead at the scene.

Confirming his death, his publicist said: "There are no further details as to the cause of death at this time."

Stars pay tribute to Prince

Carver County Sheriff Jim Olson said Prince's body had no signs of violence and there was nothing to suggest suicide.

An autopsy was completed on Friday, though the medical examiner's office says it won't release the findings until they have all the details. Spokeswoman Martha Weaver said she expected the process would take “several days” while “the results of a full toxicology scan could likely take weeks”.

Prince's body was handed over to his family following the four-hour post-mortem.

24 hours after his death, 13 of the top 20 albums on iTunes were Prince LPs (GETTY) (Getty)

Sheriff Olson and Ms Weaver refused to say whether any prescription drugs were taken from Prince's home after his death, and refused to discuss reports by celebrity news website TMZ that the musician suffered a drug overdose less than a week before he died.

Citing unidentified sources, TMZ said Prince was treated for an overdose of Percocet – the same painkiller used by the late Michael Jackson – while traveling home from Atlanta last week.

Sheriff Olson also said that emergency workers did not administer Narcan – a drug they carry to counteract drug overdoses.

He promised to fully investigate the death, saying: "This is certainly a big event internationally and nationally and I can tell you that we are going to leave no stone unturned on this and make sure the public knows what happened."