Fairfax County officials, troubled by a federal study proposing private development of a $143 million, high-speed passenger rail line to link Dulles International Airport with the Metro system, decided yesterday to conduct their own review of the project.

Several members of the county Board of Supervisors assailed the report when it was released two weeks ago, charging that it falsely suggested that rail service in the county's congested Dulles access corridor could be built without public funds.

Yesterday, the board asked its staff to analyze the federal report, which the county has not formally received, and to consider launching yet another study of various mass transit plans for the Dulles corridor.

Although they did not specifically say so, the supervisors seemed to be weighing the usefulness of producing a second study to offset -- if not refute -- the conclusions of the federal one.

"I am opposed to federal officials . . . saying this is going to be done with private funds only when all indications are it is not," said Board Vice Chairman Martha V. Pennino (D-Centreville), an outspoken critic of the original $460,000 study, which was conducted by a task force created by the Urban Mass Transit Administration.

In other actions yesterday, the Fairfax board:

*Approved a plan that would permit citizens to pay their county taxes -- in person -- by credit card.

*Rejected a staff recommendation that would have doubled the county's annual subsidy of the Health Systems Agency of Northern Virginia, a health planning body funded by local, state and federal governments that has drawn fire from Fairfax officials for opposing facilities the county wanted.

*Adopted a joint resolution with the county school board that affirms county policy to hold the growth of the county budget to a pace consistent with the rate of inflation and the increase in the county's population.

The supervisors also clashed yesterday over the state's response to a county request for information on conditions at Camp 30, the controversial Virginia prison located in western Fairfax County.

Camp 30 has become a favorite polemical whipping boy for Republicans on the board eager to take a shot at the way the administration of Democratic Gov. Charles S. Robb has managed the prison.

Last month, after Virginia officials rejected a county plan to have a consultant study the prison, board Republicans pushed through a proposal to send a lengthy list of questions about the camp to state corrections officials.

Yesterday, Board Chairman John F. Herrity, a Republican, slammed down a thick stack of papers in front of him and said that if the state's answer "had a different coloration, it would be a pile of manure."

Most of the state's response consisted of a copy of procedures and regulations to be followed at all Virginia prison camps.