Fairfax County may strip its top bureaucrats of civil service protections, a move backed by politicians who say it would make the officials more responsive and opposed by others who fear it could politicize the bureaucracy.

"You get people who get locked into a secure position and you can't get rid of 'em," said Fairfax Supervisor Thomas M. Davis III (R-Mason), who supports the proposal. "This way you can just bag 'em."

The proposal does not have the unanimous support of the county board members who will be asked to enact it. Board Vice Chairman Martha V. Pennino (D-Centreville) said she is inclined to oppose it.

"These employes have rights too," she said. "If you take them out of the merit system, they don't have the right of appeal that other county employes have."

If the plan is adopted, it would give County Executive J. Hamilton Lambert more flexibility in firing agency and department heads. They no longer would have the right to file grievances with the Fairfax Civil Service Commission.

The proposal, which could come before the County Board of Supervisors later this year, is included in a revision of the county's merit system ordinance, a statute that has not been rewritten since it was enacted in 1957. Current agency chiefs would have the option of remaining in the civil service system, but individuals named to high-ranking jobs afterward would be exempt from it.

The only county employes now exempt from the system are Lambert, his four top deputies and County Attorney David T. Stitt.

Fairfax Personnel Director Cornelius J. O'Kane has submitted the revised ordinance to the county Civil Service Commission, which will review it and forward it to the county board.

The proposal appears to enjoy support from most members of the county board, who see it as a way to make county bureaucrats more accountable and to fire those who fail to toe the line.

"Some department heads have 1,000 or more people that they're in charge of and they're making policy," said Supervisor Audrey Moore (D-Annandale). "They ought to be responsive."

The supervisors insist that there is little political influence in hiring and firing decisions in the county, and that there is no danger of subjecting bureaucrats to the political whims of the county board.

"I don't think it's going to turn into a patronage system," said Davis, "but you obviously have to watch for the excesses."

John E. Robinson, director of the Fairfax Civil Rights Commission, said that Lambert and the present county board do not seem inclined to play politics with county personnel. "But what happens when those people leave and are replaced by someone not as good or with less integrity?" he said.

Although Robinson said he did not oppose the proposal outright, he said it could open the way to firing good employes for bad -- or politically whimsical -- reasons.

Several agency heads, speaking on the condition that they not be named, also said they were uneasy with the proposal.

" It's not necessarily bad," said one agency chief, "but I'm concerned that the system gets politicized." He said that in Montgomery and Prince George's counties, where department heads are exempt from civil service protections, the bureaucracy is more vulnerable to political pressures from the county councils.

Another agency head said he would not mind losing civil service protections if the move is accompanied by an increase in pay or benefits. "With no pay incentives," he said, "there'd be no reason to give up the merit system protections."

Personnel chief O'Kane said he does not think the proposal would be accompanied by any increase in compensation for department and agency heads.

In 1981, a consultant hired by the county board recommended that agency heads be exempted from the civil service and form a so-called "executive service." The consultant's study also endorsed a steep increase in salaries for the officials, a proposal that drew sharp criticism from citizens groups.

Most Washington-area jurisdictions, with the exception of Fairfax County and the City of Alexandria, exclude department heads from the civil service. The District has about 165 employes not included in its civil service, according to Karen B. Lucas, assistant to the director of personnel.