Jackson had a sometimes troubled relationship with his 80 year-old father, who he said would sometimes beat him before sending him on stage.

The will, drawn up in 2002, is expected to be submitted to Los Angeles Superior Court later this week. It is said to have been written by John Branca, a prominent entertainment lawyer who was Jackson's attorney from 1980 to 2006. Jackson had re-hired Mr Branca shortly before his death.

In a court filing on Monday the singer's parents said they believed Jackson had died without a valid will.

But they said: "It is possible that the court will have to review many wills and evaluate the competing claims of the presenters. Someone with legal authority needs to be in place now to properly protect the estate's interests."

The Jacksons' lawyer, L Londell McMillan, said they had not seen the 2002 will. He added: "We will review any will when we see it."

Legal experts said any executor of Jackson's estate appointed by him has 30 days to come forward to petition a court.

It was not known what custody provisions the 2002 will sets out for Jackson's three children. A Los Angeles court has given the singer's mother temporary custody of the children until a hearing in July.

Members of the Jackson family spent Monday ensconced in the family home in Encino in northwest Los Angeles deciding on the funeral arrangements.

With as many as 200,000 people predicted to converge on Los Angeles the city's police chief has set aside a special unit to co-ordinate plans.

Sources said the family wanted a private service for close friends and immediate family.

But such is the interest in Jackson and his untimely death that the service would be relayed via loudspeaker to crowds who are expected to line the streets.

Joe Jackson has insisted on seeing the results of the second autopsy before he buries his son.

Having said he is suspicious of the way his 50 year-old son died he wants to make sure he is satisfied that further tests do not need to be carried out.