Speculation was mounting today about a potentially lethal drug cocktail that could have killed pop legend Michael Jackson.

See also: Michael Jackson dies

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Officials said further tests are needed.

The tests will determine whether prescription drugs played any role in the star’s death.

But reports suggested the 50-year-old performer, who died on Thursday, was taking three strong painkillers.

He is believed to have been receiving thrice-daily injections of Demerol, as well as tablets of the strong narcotic Dilaudid.

Jackson is also thought to have been prescribed Vicodin.

Police and coroner’s officials have ruled out foul play and are focusing their investigations on the role prescription drugs may have played.

Reports claim Jackson used five other medicines, including the muscle relaxant Soma, sedative Xanax and anti-depressants Zoloft and Paxil. Attention has also focused on Jackson’s doctor Conrad C Murray, who was with him when he fell ill.

The results of the three-hour post-mortem examination have been deferred, possibly for between four and six weeks, and Jackson’s body has been returned to his family.

Craig Harvey, operations chief of the Los Angeles County Coroner’s office, said there was no evidence of foul play or trauma on the superstar’s body but further tests were needed.

Meanwhile, tributes have continued to pour in to the singer. His close friend Dame Elizabeth Taylor said: “I loved Michael with all my soul and I can’t imagine life without him.”

Bee Gee Robin Gibb described the late star as a “wonderful, sensitive human being”.