The cost of full basic cable television service in Fairfax County will rise by $2, to $23.95 a month, as of Jan. 1, the highest basic rate in the Washington area, Media General Cable of Fairfax announced yesterday.

The announcement came shortly after the apparent demise of legislation being considered in Congress to restore some government oversight of cable television rates, which were deregulated as of 1987.

The bill, passed unanimously by the House in August, was derailed Friday by the objections of a handful of senators to setting a time limit on debate. Advocates of the measure still hoped to resurrect it but acknowledged that this would be difficult in the short time remaining before Congress adjourns.

Cable subscribers and consumer groups have complained that monopolistic cable franchises across the country have raised rates excessively without having to justify increases. Consumer advocates said yesterday the Fairfax rate increases show the need for the type of government reregulation proposed in the national legislation.

"Cable operators are free to jigger their prices at will, and they have been doing so," said Andrew Jay Schwartzman, executive director of the Media Access Project. "They give a mumbled justification about cost, but what they are passing on is far more than their costs. They are simply monopolies operating in an unregulated market."

In announcing its increases, Media General said that fees it pays programmers increased 24 percent this year and are expected to rise another 15 percent next year. The rate increases do not cover the company's rising expenses, according to a statement.

"It's a very modest rate increase," said Thomas E. Waldrop, Media General's chairman, in an interview yesterday. Waldrop said that the Fairfax franchise, which Media General has had since 1982, has not yet become profitable, a situation that industry analysts say is typical for urban-area cable systems at this stage.

Waldrop said the company provides 81 television channels on its full basic service, more than any other franchise in the Washington area, making the per-channel cost among the lowest in the region. The franchise has 182,000 subscribers, representing 66 percent of the homes it passes.

Waldrop said that in the past, few subscribers have canceled as a result of rate increases, but he challenged the idea that there is no competition to cable. Videocassette recorders let people watch current movies, and rabbit ears and outside antennas are available for better reception, he said.

Media General also said that its limited basic cable service would increase by $1, to $11.95, in January and that three premium channels -- Bravo, Disney and Home Team Sports -- would cost $1 more then.

Limited basic, with 43 channels, provides better reception of non-pay channels and includes public service stations, government access channels and some foreign language programming. Subscribers wanting to get the more popular channels -- such as ESPN, CNN and MTV -- must buy the full basic service. The Fairfax cable company also offers 12 premium channels, such as Home Box Office, for extra charge.

The timing of the rate increase announcement, right after the major setback for the federal legislation in the Senate, was coincidental, Waldrop said. Under the terms of its franchise, the company must inform Fairfax City of any rate increases 90 days in advance, and the company decided to make a general announcement of the 1991 increases at the same time, he said.

Gene Kimmelman, legislative director of the Consumer Federation of America, said the average cost of expanded basic service nationally is $15 a month. Although the Fairfax franchise has more channels than a typical 45-channel system, its $23.95 rate can be compared to the national average because Fairfax subscribers must buy the full basic service to get the popular channels that attract people to cable in the first place, Kimmelman argued.

"These prices are inflated to begin with," he said.

Thomas Robinson, chief of the cable regulatory division of Fairfax County, said the county wants to see the federal legislation pass so local governments would have authority to do more than review rates and provide consumer information.

"We wish we had control back, so if {an increase} did seem higher than justified, we could do something about it," Robinson said. Now, the county merely reviews the information given out by the company for its accuracy.

According to a chart provided by Media General, other franchises in the Washington area offered basic service this year for $16.95 to $21.95. Media General is among the first to announce increases for 1991.

Cable subscribers in northern Prince George's County also will see a rate increase soon, a $2-a-month rise, to $21.95, for basic service. Multivision, which operates the 60-channel cable franchise, said the increase would apply to the December bills for most of its 76,000 subscribers and to those in Bowie and Laurel in January.