Oprah Winfrey, America’s highest-earning television celebrity, is set to build on her cash mountain after selling a TV channel she co-founded to NBC Universal for about $925 million (£454 million).

NBC, home to hit shows such as ER and the US version of The Office, is buying Oxygen Media, a cable television channel aimed at women, to “increase our foothold in the advertiser-coveted young, upscale, female demographic,” according to Jerry Zucker, its chief executive.

“It perfectly complements our current roster of cable channels and plays to our strength of running and operating cable networks,” he added.

Oxygen, which was set up in 2000 and reaches 74 million homes, shows established female-centric programmes such as Absolutely Fabulous and Rosanne. It also creates original programming, such as The Bad Girls’ Road Trip, a reality series in which feisty women crisscross America visiting one another's families.

Oxygen has not revealed the ownership structure of the group, but, as a key co-founder in the group, Ms Winfrey is expected to receive a substantial windfall from the sale.

Ms Winfrey set up the group with Geraldine Laybourne, its present chairman and chief executive, and the television producers Marcy Carsey, Tom Werner and Caryn Mandabach, best know for their work on The Cosby Show.

Ms Winfrey is by far the world’s best-paid television entertainer, earning an estimated $295 million in the year to June 2007, dwarfing the second-ranking Jerry Seinfeld, on $68 million, according to Forbes magazine.

Simon Cowell, a creator and judge of American Idol, the US version of Pop Idol, came third with $51 million.

In fact, Ms Winfrey is reckoned to be the richest woman in the entertainment industry globally, ahead of the author JK Rowling, with a fortune put at £750 million.

The acquisition of Oxygen will build on NBC’s cable television portfolio, which includes the CNBC financial channel, Bravos, USA, Sci-Fi and MSNBC.

The deal will be largely funded through the sale of other NBC assets, such as two independent Telemundo television stations, one in Los Angeles and the other in Puerto Rico.

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