The head of the organization representing Northern Virginia developers said yesterday that Fairfax County Board Chairman John F. Herrity and other county officials are unfairly trying to blame developers for Herrity's alleged failure to comply with state and county public disclosure laws.

"We resent the implication that the development community is at fault for this," Samuel A. Finz, chief executive officer of the Northern Virginia Builders Association, said in an interview. "To take a situation like this, turn it around and blame it on the developers is very unfair."

Area developers "go out of their way" to obey the disclosure laws, said Finz. He added that county supervisors are ultimately responsible for disqualifying themselves from a rezoning case because of business or political relationships with companies or officials doing business with the county government.

Finz said Herrity "maybe erred in his judgment" in depending upon developers to spot potential conflict-of-interest votes when he "should have relied on the information supplied to him by his staff" and upon his own knowledge of his business associates or campaign contributors.

Finz's comments came in response to questions about Herrity's contention that developers were chiefly responsible if he violated local and state public disclosure laws on four occasions in the last year, as he has been accused of doing.

One case centers on Herrity's participation in the county's review of a rezoning case involving a business associate. In the other three, Herrity voted for development proposals involving persons who had contributed to his 1983 reelection campaign.

Fairfax Commonwealth's Attorney Robert F. Horan Jr. is in the fourth week of an investigation into whether Herrity violated the Virginia law requiring public officials to disqualify themselves from cases involving anyone with whom they share a business or financial relationship.

Horan also is trying to determine whether Herrity failed in the three development cases to comply with a Fairfax County ordinance requiring supervisors to disclose their receipt of campaign donations from anyone involved in a development proposal before participating in the county's review of that case.

In the rezoning case, Herrity participated in the county's review of a town house project in the Springfield District involving Hersand Builders Inc. Midway through the county board's review of that case, Herrity purchased an office condominium in Fairfax City with Hersand's president, Herbert L. Aman III.

In two statements on the issue, Herrity attributed his failure to disclose those relationships or to disqualify himself from the development cases to the failure of those developers to disclose their relationship with him. Herrity declined to respond to questions about the issue yesterday.

Supervisor Thomas M. Davis III (R-Mason), who has admonished developers for not taking the disclosure requirements seriously enough, said yesterday that his comments were not intended "as a slap at the development industry" as a whole.

"The problem is mutually shared by those applicants who have paid very loose attention to following disclosure law details and to the board members who aren't awake," Davis said.

At Herrity's request, the board Herrity "should have relied on the information supplied to him by his staff" and on his own knowledge of associates or contributors. -- association head Samuel A. Finz directed County Executive J. Hamilton Lambert to establish a centralized county computer system that would warn the supervisors of potential conflicts of interest before they participate in development-related votes.

Finz said yesterday that his group, which represents more than 1,000 builders, endorses such a system and believes it should have been in place before the present controversy surfaced. "My question is why it has taken them so long to do it," Finz said.