Media mogul Rupert Murdoch is stepping down as chairman of Fox and News Corp and handing control to his son Lachlan.

Mr Murdoch, 92, said in a note to employees that “the time is right” for him to move on. He will take on the honorary title of chairman emeritus of both businesses after their annual meetings in mid-November.

His decision comes months after he dropped a plan to merge the two major media assets.

The Australia-born tycoon launched Fox News in 1996 and it is now the most watched TV news channel in the US.

“Our companies are in robust health, as am I,” he said, in a note to employees partly aimed at confirming he is still in working mode.

“Our opportunities far exceed our commercial challenges. We have every reason to be optimistic about the coming years – I certainly am, and plan to be here to participate in them.

“But the battle for the freedom of speech and, ultimately, the freedom of thought, has never been more intense.”

Lachlan will remain the chief executive of Fox Corporation. At News Corp, he will be the sole chairman.

He said: “On behalf of the Fox and News Corp boards of directors, leadership teams, and all the shareholders who have benefited from his hard work, I congratulate my father on his remarkable 70-year career.

“We thank him for his vision, his pioneering spirit, his steadfast determination, and the enduring legacy he leaves to the companies he founded and countless people he has impacted.

“We are grateful that he will serve as chairman emeritus and know he will continue to provide valued counsel to both companies.”