DID AN INJECTION KILL MICHAEL JACKSON?

But he had stepped up the dosage in recent weeks as he prepared to return to the stage for a string of gruelling London concerts.

He had been due to begin a 50-night run at London’s O2 Arena next month and was rehearsing on the morning before he collapsed.

The Jacksons’ former family lawyer Brian Oxman said last night that he had become increasingly concerned over recent months that the stress of the tour and the cocktail of drugs Jackson was taking was exacting a toll on his health.

While it is expected the post-mortem will reveal Jackson died of a heart attack, toxicology reports have also been ordered to determine whether any drugs in his system might have been a contributing factor. The results will not be known for three weeks. Mr Oxman said he believed the star’s addiction to prescription drugs had contributed to his early death. He said members of the Jackson entourage “enabled” the star but did not name names.

“This is a case of abuse of medications,” Mr Oxman said.

“This is not something which had been unexpected. Because of the medication that Michael was taking, his family had been trying for months and months and months to take care of Michael Jackson.”

He added: “I don’t want to jump to conclusions, and I don’t want to point fingers. We don’t know what Michael Jackson perished from, but what I do fear is that it was the medications.”

Mr Oxman, who was at the hospital with the Jackson family when he died, revealed that the singer first started taking painkillers after his hair caught fire during the filming of the Pepsi commercial. The drugs became a regular part of his life, Mr Oxman said, when Jackson later fell off a stage and suffered a broken leg and cracked vertebrae.

“I spoke to family members, I said if this situation arises where Michael perishes because of these medications I will not hold my tongue. I will speak out and I will speak out loud about the over­medication of Michael Jackson.”

Mr Oxman said another factor was the upcoming tour dates in London which had put Jackson under intense pressure. He had already put back the opening dates at the 02 arena amid reports that he was suffering from skin cancer.

Mr Oxman said Jackson had been working hard and had hired Lou Ferringo, who played the Incredible Hulk in the TV series, as a personal trainer.

“Michael was rehearsing and working extremely hard,” Mr Oxman said. “I think he was in discomfort because he was working so very hard.” Broadcaster and pop historian Paul Gambaccini also said Jackson’s concerts in London had been a source of worry.

“It seemed to be too much of a demand on the unhealthy body of a 50 year old.

“I wonder if perhaps the stress of preparing for those dates was a factor in his collapse.

“It was wishful thinking that at this stage of his life he could be Michael Jackson again.”

Jackson’s 54-year-old brother Jermaine broke down in tears yesterday as he spoke about Michael’s death. The star’s mother Katherine, father Joe and sister La Toya also gathered at the hospital.

American president Barack Obama last night paid tribute to the singer, describing him as a “spectacular performer” and a “music icon”.

And Jackson’s ex-wife Lisa Marie Presley, 41, revealed on her website that her husband once confessed to her that he was always afraid he would end up dying of drugs like her father Elvis.