Northern Virginia's political leaders, who have maintained for years that the region was being short changed on Virginia highway funds, received support yesterday from a unlikely course -- state Highway Commissioner Harold C. King.

King, who came north from Richmond to answer angry allegations by Fairfax County officials that his department isn't fair to the Washington suburbs, at first appeared unsympathetic to the complaints.

"When total funding is considered," he told a meeting of Fairfax supervisors and state legislators, "We think you get back a little bit more than goes in [to the highway trust fund from Fairfax]."

But King later made an important qualification to his public statement. In an interview after the meeting, he said: "I was talking about total funding, including interstates. When you take out interstates, they [Northern Virginia] don't get their share.

"There is a problem," King said. "It's time for us to look at the total process of allocation. I would support a fund allocation plan that looks at mileage, population and density."

State Sen. Adelard L. Brault (D-Fairfax), who heads the county's legistative delegation, later called King's remarks "great news . . . I've never heard any state official say Northern Virginia doesn't get its fair share. This is a milestone.

"I'm glad to hear he's finally admitted it," said Fairfax Supervisor Martha V. Pennino (D-Centreville). Her rapidly growing district in the northwestern part of the county is becoming increasingly congested as formerly country roads have been transformed into major routes.

But as Northern Virginia leaders applauded King's statement, many acknowledged that the chances of soon getting more highway money for the area are slim.

"When you put more money in Northern Virginia," Brault said, "that means somebody loses funds."

Brault's ouster last week as Senate majority leader along with the retirement of Omer L. Hirst, who was a senior member of the Senate Transportation Committee, will not help Northern Virginia bargain with other areas of the state for more road money at the upcoming session of the Virginia General Assembly, the legislators said.

Area officals -- especially those from Fairfax -- have been angered that the state is funding numerous highway projects elsewhere even though the affected roads carry as few as 3,500 to 4,500 vehicles daily, the amount carried by many ordinary subdivision streets in the county.

Funds for primary and urban roads are allocated by the nine-member State Highway Commission, whose members are selected on the basis of geography instead of population. Northern Virgina, with more than a fifth of the state's population, is only a portion of a large district based in Culpeper with one representative on the commission.

Last month, William B. Wrench, Fairfax businessman who is the commissioner from Culpeper, said: "I think we're getting screwed."

King's acknowledgment that the allocation formula isn't fair to Northern Virginia is not an opinion shared downstate, even in his own agency, which traditionally has been staffed by civil engineering graduates from Virginia Military Institute and Virginia Polytechnic Institute and State University.

King's top offical at the Culpeper district office, chief engineer Donald B. Hope, said last month: "The needs of the district have been ignored to take care of Northern Virginia's funds."

King's views are, however, indicative of the thinking of Gov. John N. Dalton, Paul G. Edwards, the governor's press spokesman, said yesterday. "Hal King does represent the opinion of the administration on these issues," Edwards said. "If he said that, he is the most important source, apart from the governor himself."

At yesterday's meeting, Fairfax transportation director Shiva K. Pant said that since 1973 the county's share of miles traveled on state roads has risen from 19 1/2 to 22 percent. Fairfax's vehicle registrations have climbed from 8 1/2 to 11 percent of the state's total and its population has grown from 8 to 11 percent, he said, but that its share of secondary road funds has dropped from 11 to 8 percent.

Even if Fairfax and the rest of Northern Virginia win a more favorable allocation of road funds, the victory could be less than full. Commissioner King warned yesterday that the state is cutting back its overall plans. "We're talking about an austere [road-building] program at this time," he said. The figures [for road needs in Northern Virginia] "are so staggering we threw them out the door. You're going to have a restricted program."