WASHINGTON — A diverse group called the Coalition for Competition in Media launched a campaign on Thursday opposing the purchase of entertainment titan NBC Universal by cable television giant Comcast.

The 21 members of the coalition urged the Federal Communications Commission (FCC) and Justice Department to reject the deal as proposed, saying it poses "serious threats" to consumers and "fair competition in the media market."

The diverse coalition includes the Bloomberg news agency, the National Organization for Women, the Writers Guild of America, the National Consumers League, the National Telecommunications Cooperative Association, the National Coalition of African American Owned Media and others.

The FCC and the Justice Department are currently reviewing the deal which calls for General Electric to sell 51 percent of its stake in NBC Universal to Comcast.

The acquisition of NBC Universal would give Comcast, the largest US cable television and high-speed broadband provider, a media and entertainment empire to rival that of The Walt Disney Co.

It would combine Comcast's cable television and Internet operations with NBC Universal's vast stable of news, movie and television programming, creating an unparalleled marriage of distribution and content.

The coalition said the acquisition would "give Comcast unprecedented power nationally and in local cable markets around the country."

"If you are a local business that wants to advertise, you have to do business with Comcast and pay the prices Comcast demands," it said.

"If you are a cable customer, you either pay Comcast's prices or risk losing content that Comcast could make exclusive."

"It's far too much power for one cable company. Given the serious threat Comcast's plans pose to consumers and fair competition in the media market, the FCC and Justice Department must act to use their authority to protect the public interest," the coalition said.

NBC's cable and broadcast television holdings include flagship NBC -- the oldest of the four major US broadcast networks along with ABC, CBS and Fox -- financial news channel CNBC, 24-hour cable television news channel MSNBC, The Weather Channel, Bravo and Spanish-language broadcast network Telemundo.

Comcast operates several television channels including the Style Network, the Golf Channel and E! Entertainment Television.

A number of members of Congress have expressed concern about the deal and the House of Representatives Subcommittee on Communications, Technology and the Internet was holding a hearing about the deal in Chicago on Thursday.