LOS ANGELES/LONDON - The parents of Michael Jackson filed for guardianship of his three children Monday, celebrity website TMZ.com reported.

The court filing is the first legal move of what could become a lengthy battle for control of Jackson’s children and estate - especially if Jackson’s ex-wife Debbie Rowe, who is the mother of the two older children, attempts to overturn her previous stance waiving her parental rights over the children.

The petition was filed by Katherine Jackson, the children’s grandmother, and stated the children have “no relationship with their biological mother”.

The petition said the children are in the care of Katherine and they have “a long established relationship”. The petition says it’s “not known at this time” whether Rowe agrees that Katherine should be the legal guardian.

The filing came after a lawyer for Jackson’s father Joe Jackson revealed Sunday that the family planned to assert control over his estate and that Jackson’s mother will seek custody of his three children.

“That’s who Michael would have wanted to have the children. She loves them dearly,” lawyer L. Londell McMillan told reporters. He said the children are in “great care” and in a “loving environment” with their grandmother Katherine at the family’s Encino estate.

NBC Dateline reported meanwhile that Jackson was taking a mixture of powerful sleeping aids and anti-anxiety medicine at the time of his death Thursday and there was no evidence of the narcotic painkiller Demerol in his system, NBC Dateline reported Monday.

Quoting sources in the police investigation of Jackson’s death, the report appeared to put paid to widespread speculation that the King of Pop was addicted to narcotic painkillers that led to cardiac arrest and his death.

The report came as Britain’s The Sun said that the autopsy had shown Jackson weighed only 51 kg on his 1.77 metre frame, and that his body was wracked with numerous needle marks and evidence of multiple plastic surgeries.

No plans have yet been announced for Jackson’s funeral arrangements.