Los Angeles  - The Los Angeles coroner has found that Michael Jackson died from a lethal dose of the tightly controlled hospital anaesthetic propofol, according to court documents released Monday.

The finding was contained in the search warrant for the home of Jackson's physician, Dr Conrad Murray, 50, whose Houston, Texas, home was searched by law enforcement officials on July 22, looking for evidence of manslaughter.

"The Los Angeles chief medical examiner-coroner, Dr Sathyavagiswaran, indicated that he had reviewed the preliminary toxicology results, and his preliminary assessment of Jackson's cause of death was due to lethal levels of propofol (diprivan)," according to the search warrant affidavit released by the Harris Country District clerk.

The search warrant quoted Murray, 50, as saying that he had treated Jackson for insomnia for six months using propofol, regularly giving him 50 milligrams of the drug via an intravenous feed. Murray claimed that he had been trying to wean the pop star off the powerful drug and on the day he died, Jackson only received a 25-milligram dose.

Nevertheless, the warrant exposed a potent drug cocktail that Murray had administered to Jackson in the hours before his death, including valium and other sedatives including lorazepam and midazolam and ofmidazolan. When none of these helped Jackson sleep, the doctor gave him the propofol diluted with painkiller lidocaine.

Murray told investigators he left the room for 10 minutes to use the bathroom, and when he returned Jackson was not breathing, the warrant said.

Propofol is usually used only as a hospital anaesthetic, and the discovery of lethal levels in Jackson's system is likely to increase speculation that Murray will face manslaughter charges over the June 25 death of the pop star.

Murray's records did not reveal any prescription for Propofol, and it is unclear where Jackson obtained the drug, the affidavit said. Murray was quoted as telling investigators that Jackson had been treated with propofol by two doctors in Germany.

Following release of the warrant, the Jackson family issued a statement backing law enforcement efforts.

"The Jackson family has full confidence in the legal process, and commends the ongoing efforts of the LA County coroner, the LA district attorney and the LA Police Department. The family looks forward to the day that justice can be served," they said. (dpa)