The Fairfax County supervisors, confronting one of the county's most sensitive development issues, last night adopted a plan by a citizen task force designed to derail attempts by area developers to increase the heights of buildings at Tysons Corner.

In a 6-to-0 vote, the board adopted a policy embracing the view of Tysons area residents that developers should be discouraged from seeking greater heights than those now permitted in the 1,700-acre Tysons Corner area.

The supervisors also signaled their support for the residents' position that construction of tall buildings on the perimeter of Tysons Corner poses a threat to neighborhoods and should be prohibited.

The county planning staff, in a move backed by developers, originally had recommended that zoning regulations along the Tysons perimeter be relaxed to allow the construction of buildings as tall as 22 stories to stand as "gateways" to the county's foremost commercial area.

With its decision, the board rejected the county Planning Commission's recommendation last week that essentially dismissed the residents' proposals.

Supervisor Nancy K. Falck (R-Dranesville) said the county board's action recognized that the rapid buildup of Tysons Corner must be brought under control.

Falck said that although development at Tysons has helped keep the county's tax and unemployment rates down, it is saddling the county with other problems, particularly traffic. Falck, who was instrumental in the approval of the mammoth Tysons II project, which is to include a shopping mall, an 11-building office park and two hotels, has come under criticism from Tysons area residents who say she has sided too often with developers.

Last night she said exactly what those residents wanted to hear.

"We've got enough there," Falck said of development in the Tysons area.

"It is time in my opinion to move to some other area for that kind of high-density office and commercial development. We've got all we can chew in that area."

Board Chairman John F. Herrity, a Republican, agreed, declaring that the county's action will thwart the expansion of Tysons beyond its present boundaries and protect residents of nearby neighborhoods.

The board's action was hailed by members of a citizen task force impaneled by the board 15 months ago to examine the height issue.

"We feel this will contain the spread of Tysons Corner," said Stephen Hubbard, chairman of the planning and zoning committee of the McLean Citizens Association, which played a major role in the study. "We got a major document that provides guidelines for the future development of that area."

The county authorized the study largely in response to a surge of attempts by developers to build well beyond the height limits the county had established for Tysons Corner. Most troubling to residents and county officials concerned about the trend were the variances that allowed construction of the 215-foot Sheraton Hotel at Rte. 7 and the Dulles Access Road and the 204-foot Tycon Towers at Rte. 7 and the Capital Beltway.

The height limit for buildings in those areas had been 75 feet.

Voting last night to adopt the residents' report were Herrity, Falck, board Vice Chairman Martha V. Pennino (D-Centreville) and Supervisors Audrey Moore (D-Annandale), James M. Scott (D-Providence) and T. Farrell Egge (R-Mount Vernon). Three supervisors were absent from the meeting: Joseph Alexander (D-Lee), Thomas M. Davis III (R-Mason) and Elaine N. McConnell (R-Springfield).