Rupert Murdoch is locked in a secret legal battle against three of his children over the future of the family’s media empire, as he moves to preserve it as a conservative political force after his death, according to a sealed court document obtained by The New York Times.

Mr. Murdoch, 93, set the drama in motion late last year, when he made a surprise move to change the terms of the Murdochs’ irrevocable family trust to ensure that his eldest son and chosen successor, Lachlan, would remain in charge of his vast collection of television networks and newspapers.

Rupert Murdoch is engaged in a legal fight with some of his children, as he tries to hand control of his media empire to his eldest son, Lachlan, a battle with major ramifications for the future of the mogul’s two companies.

Murdoch, 93 years old, controls a trust that holds the family’s substantial stakes in News Corp NWSA 1.06%increase; green up pointing triangle, parent of The Wall Street Journal, and Fox News parent Fox Corp. Under its terms, when Murdoch dies, voting control would pass to four children—Lachlan, James, Elisabeth and Prudence.

Rupert Murdoch is involved in a legal battle with his children over his plans to hand over his global media empire to son Lachlan, according to a report. 

The fight for power between the 93-year-old mogul's four eldest children appeared to be decided when Lachlan emerged as the designated heir.  

But Murdoch is now fighting to extend his eldest son's voting power in the Murdoch Family Trust, the New York Times reported.