Doctors performing an autopsy on the body of singer Michael Jackson have ruled out foul play in his death.

However they have said that toxicology tests have been ordered and determining the cause of death could take several weeks.

Los Angeles county coroner spokesman Craig Harvey said that police had put a security hold on Jackson’s case which limited the amount of information which could be released to the public.

However he said that a three hour post mortem had taken place and the cause of death had been deferred. “It means that the medical examiner ordered additional testing such as toxicology and other studies,” Harvey added.

He said these would take around four to six weeks.

The singer’s body has now been released to his family although as yet no funeral details have been confirmed.

Jackson, who was 50, died on Thursday after suffering a cardiac arrest at his home in Los Angeles.

Tributes have been flooding in for the singer, who was due to stage 50 concerts at London’s O2 Arena beginning next month.

Madonna and Justin Timberlake are among those singers who have paid tribute, while Paul McCartney, who released two singles with Jackson in the early 80s said the news was “so sad and shocking”.

A spokesman for US President Barack Obama said that the president saw the 50-year-old as a “music icon” but that parts of his life had been “sad and tragic”.