Police in Los Angeles are treating Michael Jackson's death as a homicide case, according to US media reports.

Entertainment website TMZ claims the investigation has now focussed on the singer's former physician, Dr Conrad Murray.

A law enforcement source told the website there was “powerful evidence” that Dr Murray administered the drug Propofol into Jackson's body.

The sedative, also known as Dirpivan, is commonly used to help induce a patient into unconsciousness before surgery.

TMZ, which broke the original story of Jackson's death on June 25, claims police have collected a variety of evidence, including an IV stand and an oxygen tank, from Jackson's former home.

Last week, Chief William Bratton, who is leading the investigation, said detectives had yet to rule out homicide as a possible cause of death.

Bratton told CNN they were awaiting the results of toxicology tests, which are reportedly due this week or next.

Jackson died following a suspected cardiac arrest at his Los Angeles home, which he was renting ahead of his ill-fated concert comeback in London.

(by Jason Gregory)