Pop icon Michael Jackson was clinically dead long before medical help turned up at his LA home, a report said on Sunday.

Paramedic chiefs and staff at UCLA hospital have revealed to the News of the World, details of the report which was overseen by three specialist paramedics.

The report made on a comprehensive official form, makes clear that the King of Pop had already got no pulse, there was no sign of heart activity and he had stopped breathing.

But the star's body showed clear signs of lividity - a condition when the blood drains to the bottom of the body after the heart stops.

Dead body takes at least three hours to show signs of lividity, a doctor at the News of the World said.

The report is contrary to the claim of Jackson's personal physician Conrad Murray who said the singer had a faint pulse at the house and so would have benefited from CPR on the way to the hospital.

Dr Steven Hoeffin, a close friend of Jackson confirmed the findings of the report and said that the chief in the fire department told him that Jackson was dead when they arrived.

"He had no pulse and was not breathing. They gave him an electro-cardiogram but he was flat-lined," the News of the World quoted Hoeffin as saying.

"They say he even had lividity, which meant the blood had sunk to the back, indicating his heart had stopped a couple of hours earlier," Hoeffin said.

"This is the most important aspect of the report as it means he must have been dead for over an hour, probably longer," he added.