Fairfax County Board Vice Chairman Martha V. Pennino yesterday harshly attacked a new proposal to provide high-speed rail service to Dulles International Airport, accusing a federal task force of misleading the public about who would pay for the service.

"The concept of a rail system is excellent. In fact, it's long overdue," Pennino, a Democrat, said. "But this notion that it would be built without public funds is fallacious."

"This is another p.r. job . . . . We're being took," she said. "For nothing you get nothing -- somebody always pays. In this case it's the commuting public and the general public."

Officials of the U.S. Department of Transportation task force, which is expected to endorse a consultant's report outlining the rail proposal on Tuesday, responded yesterday that criticism of the plan is premature.

The $460,000 report, released Friday, concluded that a 16-mile line linking Dulles with the Metro system could support itself from operating revenues. It said that the $143 million railway could be constructed by a private builder without federal money through a novel financing plan that would increase property taxes on new commercial developments along the line and with higher tolls on the Dulles Toll Road.

"They're talking about taxing land -- that's public funds. They're talking about raising the toll rate -- that's public funds," said Pennino. "If a rail line is going to be built, it should be built by a public authority."

Fairfax Board Chairman John F. Herrity, a Republican, also criticized the proposed method of paying for the rail line Friday, expressing concern that the plan counts on greater development along the Dulles Access Road than is allowed by the county's master plan. Yesterday he called for a county consultant to examine the proposal, saying, "We have to look at this with some degree of skepticism."

"This proposal deserves serious consideration," he said, but it should be compared to other proposals such as widening the roads approaching Dulles.

The plan would require approval of the conservative Virginia General Assembly, which some Fairfax officials said is unlikely to grant the taxing authority to the county.

The chairman of the Dulles Airport Access Task Force, Paul M. Weyrich, acidly dismissed the criticisms yesterday. "I wish that members of the Fairfax Board of Supervisors would cease reacting until they have at least seen the report," Weyrich said.

He emphasized that the primary finding of the report is that a rail system can be maintained from the money raised by fares, and that the proposal to pay for construction is not a formal recommendation, only a possibility that should be explored.

"Quite clearly it can be operated on its own revenues," he said. "The question is how to pay for it. This report only names a number of options," he said, adding that the report considered only options that would be permissible under current county plans.

Weyrich said that at least two corporations -- one of them a firm formed by a foreign government that he would not name -- are interested in picking up the tab for construction of the rail line so that it could become an advertisement for their business in the nation's capital.

"I'm taking that possibility seriously . . . . There's a better than 50 percent chance," Weyrich said.

Ralph L. Stanley, head of the Urban Mass Transportation Administration, which assembled the task force, yesterday rejected Pennino's charge that officials are fraudulently promoting the rail line as an entirely private venture.

"It was not based on the premise that there would be no public funds. It was based on the premise that there would be no federal funds," Stanley said.

Some members of the Fairfax board were more optimistic about the Dulles rail proposal yesterday. "I haven't read the report yet," said T. Farrell Egge, a Republican. "But if a private group can make a rail line viable with private funding, more power to them . . . . We should definitely consider it."