Comcast Corp on Thursday named several executives who will hold top jobs at NBC Universal after the cable company takes control of the broadcaster and movie studio.

Former Showtime President Bob Greenblatt will be chairman of NBC Entertainment, responsible for prime time and late night programming, business affairs and NBC Universal Media studios.

Greenblatt's appointment, revealed in a company memo, is seen as the most high-profile because Comcast will strive to improve NBC's poor broadcast ratings of recent years lagging behind CBS, Fox and ABC.

The memo was written by incoming NBC Universal Chief Executive Steve Burke and obtained by Reuters. It follows weeks of speculation in Hollywood media.

Current NBC chief Jeff Gaspin told staff in a memo earlier this week that he would leave after the transaction closes. NBCU Chief Executive Jeff Zucker said last month that he would leave after the deal closes.

The cable networks business will be split between Bonnie Hammer, as chairman of NBC Universal Cable Entertainment and Cable Studios including USA, SyFy, E! and G4, while Lauren Zalaznick will be chairman of NBC Universal Entertainment & Digital Networks and Integrated Media. Bravo, Oxygen and iVillage will continue to report to her.

Ron Meyer will remain as president of Universal Studios while Adam Fogelson will continue as chairman of Universal Pictures.

Dick Ebersol will become chairman of the NBC Sports Group including NBC Sports, The Golf Channel, Versus and the Comcast Regional Sports Networks. Analysts have said Comcast will bulk up its sports offerings to be able to compete more effectively with Walt Disney Co's ABC and ESPN.

Burke said in his note that none of the new roles become official until the deal closes.

Comcast revealed its bid to buy a controlling stake in NBC Universal from General Electric on Dec. 3 last year to create a $30 billion business including broadcast, cable networks, movie studios and theme parks.

Talks between Comcast's representatives and U.S. regulators have intensified in recent days, according to sources, as the company tries to complete the deal by year-end.

Regulators are "likely to impose significant conditions" on the new business, a source told Reuters.