A bitterly divided Federal Communications Commission dealt a potential blow to the nation's commercial broadcast interests yesterday by proposing a dramatic increase in the number of VHF television stations. The proposal could result in a new commercial television station in the Washington area.

FCC staff members estimated that the proposal, if adopted in final form next year, could add as many as 139 new stations in the nation's top 100 markets and offer the potential for a new national network to challenge the dominance of the three existing major television networks.

The VHF (Very High Frequency) television band is received on channels 2 through 13. The most lucrative commercial television programming is generally carried on the VHF band.

By a 4 to 3 vote, the commission rejected the pleas of national broadcasters and other advocates of UHF (Ultra High Frequency) services, concluding that the new stations could add diversity to the nation's airwaves.

But FCC members who long have encouraged UHF broadcasting attacked the decision. FCC member James Quello said the decision "is potentially damaging to this nation's television system because of interference to existing service and the disruption and confusion to consumers.

"It could well result in disservice to the overall public, minorities and majorities alike, with inferior, inadequate or lost service," Quello said in a dissenting statement.

John Summers, executive vice president and general manager of the National Association of Broadcasters, the leading industry trade group, also was sharply critical of the FCC action.

"At a time when UHF is finally beginning to solidify itself in the television marketplace, it is unfortunate that the commission is proposing to shoehorn in some 140 possible new VHF television station," Summers said. "Such a move is sure to undercut the growth and health of UHF service."

But metropolitan Washington television viewers could be among the beneficiaries of the decision. FCC officals said that if the proposal is ultimately adopted a new channel 8 or channel 10 could be available within several years.

However, officials also note that the proximity of three VHF stations in Baltimore means the new station would have to be directed in such a way that it would not block or dramatically conflict with Baltimore signals.

Establishment of the new stations, known as "drop-ins," run counter to basic FCC policy of the past 30 years, which has generally relied on limiting VHF growth by enforcing strict mileage separations between stations using the same or adjacent channels.

Under the new proposal, new stations could be allowed on the air 100 miles from stations operating on the same channel number and 35 miles from adjacent channels.

The debate within the FCC focused on whether the commission was abandoning its commitment to fostering the development of UHF stations, which require greater transmission power to cover a metropolitan area than VHF stations.

But the four members of the commission who endorsed the proposal noted that UHF revenues have dramatically increased in recent years and concluded that it is time for the FCC to drop its consistent opposition to new VHF stations.

But FCC Chairman Charles Ferris said that the new VHF stations could benefit all television outlets. "This action could lead to creation of a fourth commercial network based on short-spaced VHFs in some markets, UHFs in others," Ferris said.

"This development could not only strengthen network affiliated UHF, but also attract viewers to the UHF band generally, making other UHF operations more attractive," Ferris said.

The decision yesterday is likely to only add to the increasing criticism of this commission by network executives, who say the FCC has been discriminating against existing stations and networks in favor of adding new outlets for viewers.

Just last week, the commission proposed licensing potentially thousands of new low power stations to serve particular audiences.

The full-scale stations proposed in the "drop-in' proceeding are not likely to be targeted to specialized interest or ethic groups and would be subject to the same type of programming rules the FCC uses in regulating existing stations.