A Los Angeles judge has ruled that Michael Jackson's mother can challenge the administrators of his estate without losing her share in a lucrative family trust, according to court papers released on Friday.

Attorneys for Katherine Jackson have said she wants a greater say in the way the Thriller singer's estate -- estimated to be worth about $400 million -- is administered. It was not immediately clear if she would now formally lodge a challenge.

Jackson appointed his longtime attorney John Branca and music executive John McClain as executors of his estate in a 2002 will. Katherine Jackson's attorneys had asked the court to say whether she could make the challenge without violating a no contest clause in the family trust.

The family trust provides Katherine Jackson, 79, with 40 percent of the estate, the singer's three children with another 40 percent and children's charities with 20 percent.

According to Friday's court documents, Judge Mitchell Beckloff ruled that Katherine Jackson would not violate the no contest trust clause by mounting a challenge.

In one instance of her misgivings, her attorneys last month objected to a deal struck by the executors with concert promoter AEG Live for a memorabilia exhibition, saying they questioned whether the deal generated enough money for the estate.

Jackson left about $400 million in debts when he died on June 25 of a prescription drug overdose. But his assets, including partial ownership of the Sony/ATV music catalog and many songs by the Beatles, are estimated to outweigh his debts by at least $200 million.

Branca and McClain have said they expect album sales, licensing deals, business partnerships and a movie featuring his last rehearsal footage to boost the estate by $200 million, before the end of the year.

Police are still investigating Jackson's death and the doctors who treated him.

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