The Fairfax County Board, in a move that may signal increased tensions between the county government and Northern Virginia builders, sharply increased yesterday the fees builders must pay to the county.

The increase, effective next week, will affect the building industry as it heads into the heavy spring construction period. It is expected to add hundreds of dollars to the price of a single-family house by this fall, as builders pass on the new costs to home buyers.

The County Board approved the fees increase unanimously, despite the strong opposition of builders who threatened to seek state legislation curtailing the ability of local governments to impose some of the charges.

"We'd like the General Assembly to look at the authority of local government to impose some of these fees," said Samuel E. Finz, chief executive officer of the Northern Virginia Builders Association.

County supervisors belittled the objections. "The whole thing is peanuts," said Supervisor Thomas M. Davis III (R-Mason). "It's less than 1 percent of the cost of buying a house."

In other action, the County Board cleared the way for the private development of a large new government center in the Fair Oaks area by rezoning 217 acres there for commercial and office use. In two 4-to-3 votes, the board rejected bids by Board Chairman John F. Herrity to reduce the amount of that land that will be reserved for the government complex itself and provide more of it to a developer.

The board agreed to seek a meeting with D.C. Mayor Marion Barry to register objections to the proposed expansion of the District's Lorton Reformatory in southern Fairfax County.

The issue of how much Fairfax charges builders in fees is a symptom of the strained relations between county politicians and one of their most politically potent constituencies.

County officials were irked that the Northern Virginia Builders Association, the industry's lobbying arm, did not give them notice of legislation in the Virginia General Assembly session that ended Saturday that will force the county to hasten its review of builders' preliminary plans.

Under the fees plan that the County Board approved yesterday, county officials said, builders soon may have to pay more than $1,000 in fees on a house that might sell for $120,000, an increase from the current level of $644.

Yesterday, several supervisors took a hostile tone toward Finz, the builders' lobbyist, when he acknowledged that the builders association may seek state legislation to cap county fees.

Davis, noting what he called "the contempt with which the builders hold the board," vowed "to fight any effort any effort to let Richmond take over our process."

Fairfax adopted a policy two years ago that 85 percent of the cost of administering its Department of Environmental Management, which is in charge of monitoring construction, is to be covered by fees charged to builders.

County officials say that the feverish pace of construction in the county has led to sharply higher costs to the department this year as it struggles to stay abreast of the deluge of plan reviews and inspections. They say fees had to be increased to keep pace with those costs.

But Finz argued that the county has chosen to increase costs rather than become more productive. He said state law should be changed to allow builders to avoid direct governmental reviews and to contract with engineering firms for inspections and tests.

On the government center rezoning, the board split in two votes on the question of how much of the 217-acre county-owned parcel should be reserved for the complex and how much should be traded to a developer who would build the center.

Herrity, who for years opposed a new government center as too costly, proposed that 70 acres of the land be set aside for the complex. When only Republican Supervisors T. Farrell Egge of Mount Vernon and Nancy K. Falck of Dranesville joined him in that proposal, he urged that the board set aside 85 acres for the complex. That motion failed by the same 4-to-3 vote.

By approving a 100-acre site for the government center, the board effectively ensured that the remaining 117 acres will be relatively densely developed.