A combined Comcast-NBC would result in less media diversity and increased cable rates, a Vermont senator wrote in a Tuesday letter to the Federal Communications Commission.

Sen. Bernie Sanders, a Vermont Independent, asked the commission to reject Comcast's $6.5 billion bid for a majority stake in NBC Universal.

"At a time when a small number of giant media corporations already control what the American people see, hear, and read, we do not need another conglomerate with control over the production and distribution of sports, news, and entertainment," Sanders said in a statement. "In my view, we need more media diversity, more local control, more points of view – not more media concentration."

Comcast and NBC announced plans for a merger in December 2009. Not surprisingly, the deal attracted some regulatory scrutiny; the FCC and Department of Justice are reviewing it.

Comcast chief executive Brian Roberts and Jeff Zucker, then-president and CEO of NBCU, appeared on Capitol Hill earlier this year to defend the plan. When asked about possible rate hikes, Roberts said at the time that Comcast faces competition from a variety of companies and does not believe anything in the NBCU deal would "incentivize us or cause us to raise rates."

In May, the FCC extended the public comment period for the Comcast-NBC deal because it had not received additional economic data requested from the companies supporting their deal.

Earlier this week, the Washington Post reported that the DOJ and FCC would approve the merger provided the companies allow their competitors access to Comcast and NBC's library of network shows and movies. On Sunday, the Wall Street Journal also said both agencies have picked up the pace with their reviews in the hopes of getting it done by year's end.

Sen. Sanders, however, said approving the deal would put other content providers at a competitive disadvantage because Comcast could charge independent producers higher feeds and offer them less desirable placement on cable channel lineups. He pointed to a study from former FCC chief economist William Rogerson that said consumers would pay $2.4 billion in additional fees if the merger was allowed.

"I would think it an obvious conclusion that 'public interest, convenience, and necessity' would not be served by a regressive wealth transfer of $2.4 billion from ordinary citizens to what would be one of the largest corporate entities in the United States," Sanders wrote.

Sena Fitzmaurice, vice president of government communications for Comcast, disagreed.

"The overwhelming record in support of the Comcast NBCU transaction show the significant public interest benefits that it will deliver, including more independent programming choices, more opportunities for ownership diversity, more local public affairs programming, more viewing options for families and children, and accelerating the 'anytime, anywhere' video future consumers want," Fitzmaurice said in an e-mail. "The FCC has heard support from over 400 elected officials from coast to coast, along with countless community organizations and groups representing diverse communities."

Rogerson's analysis has been "thoroughly rebutted," she continued. "With regard to transition and integration planning, this is common, proper, and expected in a transaction of this type. At every step of the way, this process has been supervised by counsel to ensure faithful adherence to the rules, and that will continue."