NEW YORK — Lachlan Murdoch abruptly resigned as a senior executive of News Corp. yesterday, ending his father Rupert's hopes that he might run the global media conglomerate.

The younger Murdoch, 33, will move back to Australia with his wife and son and remain a director of the company.

The unexpected move is sure to fan speculation over who will succeed Rupert Murdoch as CEO of News Corp. He is 74 but has not given any indication of when he plans to step aside.

Murdoch, whose family controls 30 percent of the company, has been grooming his sons as potential heirs to his throne, giving them greater degrees of responsibility.

Lachlan had been seen as his father's favorite potential successor, though investors have been dubious that he was ready to take the helm. Lachlan's departure puts more pressure on News Corp. to clarify its succession plans.

Chief operating officer Peter Chernin is a highly regarded executive who has broad responsibilities in running News Corp.'s far-flung businesses. Lachlan was deputy chief operating officer of the company since 2000, working closely with Chernin and overseeing the conglomerate's U.S. television stations, the New York Post and other businesses.

Attention will now turn to Lachlan's younger brother James, who runs BSkyB, a British satellite broadcasting business that is about 36 percent owned by News Corp.

James, 32, had been CEO of News Corp.'s Asian satellite broadcaster Star Group Ltd. and also held other senior posts at News Corp., including executive vice president.

James gave up his positions at News Corp. in 2003 as well as a seat on the company's board when he took the reins at BSkyB. His appointment there raised opposition from shareholders.

Lachlan began his career with News Corp. in his father's native Australia in 1994. He began with cleaning presses at the Mirror newspaper, and took increasingly senior positions at the Australian newspapers.