One of Michael Jackson's bodyguards has testified that as the singer's lifeless body lay on a bed in his mansion, he obeyed a doctor's instructions to bag up medicine bottles and intravenous bags.

Alberto Alvarez told a court in Los Angeles on Wednesday he was also ordered to shield the Jackson children from seeing their father, all before being told to call an ambulance.

Alvarez said he was the first security guard to reach Jackson's room that day. The testimony came during a preliminary hearing to determine if Conrad Murray, the singer's personal physician, will be tried on a charge of involuntary manslaughter. Authorities contend Murray gave Jackson a lethal dose of the powerful anaesthetic propofol and other sedatives in the bedroom before he died. Murray has pleaded not guilty, and his attorneys have contended he did not give Jackson anything that should have killed him.