Murdoch, 31-year-old daughter of News Corp chairman Rupert Murdoch, said she had been considering the move for some time and wanted to branch out with her own venture specialising in television, film and new-media content.

BSkyB, whose shares slipped to trade 1.04 per cent down at 17.20 pounds, said director of broadcasting Mark Sharman would temporarily take over Murdoch's role as managing director of Sky Networks, running the content side of the business. Elisabeth Murdoch has often been seen as marginalised within her father's corporate structure, with two brothers vying to succeed the 69-year-old Rupert who recently revealed that he was suffering from low-grade prostate cancer.

Rupert Murdoch last year signalled that if he should no longer be able to run the company his chosen successor within the family would be 29-year-old Lachlan.