Doctors have completed an autopsy on the body of Michael Jackson but the cause of death has been deferred.

Spokesman for the Los Angeles coroner's office, Craig Harvey, said that additional testing will need to be carried out - including toxicology tests.

He added that there was no evidence of external injuries on Jackson's body or foul play associated with his death.

The further testing will take between four and six weeks.

Meanwhile, rumours surrounding the cause of Michael Jackson's fatal heart attack have raised questions over his alleged use of powerful painkillers.

Brian Oxman, who has acted as the Jackson family's lawyer, said the 50-year-old singer had taken medication over a long period and had used it after falling off stage, breaking his leg and injuring his back.

Mr Oxman - who said Jackson also took medication after his hair caught fire during the filming of a Pepsi ad in 1984 - was concerned about the star's use of painkillers while his family was worried about "stress" and his ability to perform at his upcoming shows.

The self-styled King of Pop died after suffering a suspected heart attack at his home in Holmby Hills, Los Angeles. Doctors battled for an hour to try and save him but he was pronounced dead at UCLA medical centre.

His brother Jermaine Jackson said: "My brother, the legendary King of Pop, passed away on Thursday June 25 at 2.26pm.

"We believe he suffered a cardiac arrest at his home, however the cause of his death is unknown until the results of the autopsy are known. The personal physician who was with him at the time attempted to resuscitated him."

A spokesman for the hospital added: "When he arrived at hospital at approximately 1.14pm, a team of doctors including emergency physicians and cardiologists attempted to resuscitate him for a period of more than one hour. They were unsuccessful."

TV footage showed a rescue helicopter flying the star's body to a waiting ambulance.

Tributes from the world of music, film and celebrity have flooded in.

Sir Paul McCartney said of Jackson's death: "It's so sad and shocking. I feel privileged to have hung out and worked with Michael."

Jackson's first wife Lisa Marie Presley said: "This is such a massive loss on so many levels, words fail me."

Madonna said: "The world has lost one of its greats but his music will live on forever."

The head of the Sony Corporation Sir Howard Stringer said: "Michael Jackson was a brilliant troubadour for his generation, a genius whose music reflected the passion and creativity of an era."

And Justin Timberlake - who has been compared to a young Jackson - said: "We have lost a genius and a true ambassador of not only pop music, but of all music."

Jackson was about to embark on a comeback tour - This Is It, including 50 dates in London, which aimed to resurrect his fortunes.

Jackson last toured 12 years ago when he played 82 shows in 58 cities around the world for the HIStory tour.

Lighting director Patrick Woodroffe, who had been working with Jackson in Los Angeles on rehearsals for his London shows, said that in the last few days the singer appeared to have recaptured his old form.

He said: "He was frail, you might say, but something seemed to happen over the weekend and when he came into rehearsal on Tuesday something really extraordinary seemed to happen.

"He came on stage at 9 o'clock in the evening and we all looked at each other and there was something that said that he really had it. Last night particularly, he came on stage and he was electric.

"It was like he had been holding back and suddenly he was performing as one had remembered him in the past."

Close friend Uri Geller said: "I guess the stress, the anticipation and the passion he was emitting from his heart, wanting to do this comeback so badly, maybe that got to him.

"That is all I can think, that maybe the stress killed him."

Jackson has three children, Michael Joseph Jackson Junior, Paris Michael Katherine Jackson and Prince "Blanket" Michael Jackson II.

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