Fairfax County supervisors angrily accused the Virginia General Assembly yesterday of shortchanging the Washington suburbs in transportation funding, disputing the claims of area legislators that the region this week scored a major victory in Richmond.

The supervisors criticized the legislature for approving a 3 percent tax on wholesale gasoline sales without changing the formula by which road funds are distributed. They said even the $10 million annual increase in state contributions to the Metro transit system is not the windfall it appears to be because not enough of the funds are earmarked to meet Metro's rapidly rising operating costs.

"I know they always say, 'Don't look a gift horse in the mouth,' " Democratic Supervisor James M. Scott said. "But it looks like this horse has no teeth."

After a hastily arranged lunchtime meeting with Fairfax Sen. Adelard L. Brault, the legislator promised to seek some clarifying amendments and the supervisors were somewhat mollified. They continued to maintain, however, that the gasoline tax package, approved at dawn on Sunday after hours of negotiations, would not help Northern Virginia as much as Brault and others have claimed.

"That just shows the total idiocy of the Fairfax Board of Supervisors and their total ignorance of what went on down there," said Del. Warren G. Stambaugh, an Arlington Democrat who helped forged the tax compromise. "They're exactly the reason we have so much trouble in Richmond."

Stambaugh and his colleagues spent much of the past two months debating how much to raise the gasoline tax and how to distribute the revenue. When they finally approved a $263 million compromise highway bill shortly before 3 a.m. Sunday, area legislators said Metro and the Washington area had come out on top.

"It's just the greatest victory we've had since I've been down there," Brault said yesterday after meeting with the Fairfax board. The senator is the dean of the area's delegation and has spent 17 years in the legislature.

John F. Herrity, the Republican chairman of the board, had a different assessment. "It's a transportation disaster, and it's something we're going to have to live with until they have to raise the gas tax again," he said.

Democratic supervisors in Fairfax, where officials are particularly sensitive to Metro funding issues because the county's first rapid rail station has yet to open, and officials in Arlington and Alexandria were less gloomy. Alexandria Mayor Charles Beatley said he was pleased with the General Assembly action.

"I fail to see why anyone would look a gift horse in the mouth," Beatley said. "It sounds like they're quibbling over technicalities."

The "technicality" that most concerned the Fairfax supervisors was the distinction between Metro construction and borrowing costs, on the one hand, and regular operating costs on the other. The General Assembly earmarked $41 million for Metro for the next two years, nearly double the current rate of state support, but specified that the dollars should go only for construction and borrowing.

At the same time, the legislature rejected a planned increase from 2 to 4 percent in the regional retail gasoline tax. The funds from that tax rise--about $17 million over two years at the current price of gasoline--could have been spent to meet Metro's operating costs, the critical supervisors said.

"Our difficulty as a funding participant is the operating subsidy, more so than the debt," said Arlington Board Chairman Stephen H. Detwiler, who cautioned that he had not yet seen the bill approved Sunday. "We need to find ways to take that off the backs of the taxpayers in the local jurisdictions."

The federal government has insisted that the Virginia jurisdictions commit a source of "stable and reliable" revenues to Metro before it releases more federal subway construction money. The Fairfax supervisors expressed doubt that the government would accept the $41 million commitment without the 2 percent gasoline increase, although Brault said he was confident it would.

"It is murky, to say the least," said Democratic Supervisor Joseph Alexander, who represents Fairfax on the transit system's board of directors. "It concerns me because over the years we've tried to establish an alternative, regular revenue source, and the regional gasoline tax was it."

Northern Virginia gasoline retailers had opposed the 2 percent increase, arguing that drivers would buy gasoline in Maryland or the District if the price rose too much. In addition, some said the regional tax costs the Washington area more than a wholesale tax that is distributed statewide.

Still, some local officials were disappointed that the legislature approved the wholesale gasoline tax--which almost everyone agreed the cash-strapped highway department needs--without giving Northern Virginia a greater share of road funds. The area delegates had tried to form a coalition with representatives of other fast-growing areas in Virginia that feel shortchanged, but they fell one vote short in the House.

"The failure to get anything on the allocation formula was unfortunate, because we can't survive on what we're getting," Alexander said.

Stambaugh was incredulous that the supervisors were not more appreciative of the increase in Metro funding. "You bring them back a $20 million increase in funding to one of the major cost drains here, and they say, 'It's not enough, it's not enough,'" he said. "I just hope I have another chance to do them a favor sometime."