Conservative Republican activist Paul M. Weyrich endorsed Democratic Supervisor Audrey Moore yesterday in the race for chairman of the Fairfax County Board and denounced Republican incumbent John F. Herrity as the "wholly owned subsidiary" of Northern Virginia's most prominent developer.

"There's no doubt in my mind that he is a tool of {John T.} Til Hazel," Weyrich, an Annandale resident, said in an appearance with Moore at her campaign headquarters.

Weyrich's accusations came one day after Herrity alleged that his opponent was campaigning on innuendo and touched off an angry blast of countercharges.

The Herrity campaign branded Weyrich's comments irresponsible and said they confirmed Herrity's assertion Tuesday that Moore was falsely portraying him as being "in the pocket of developers."

Moore repeated that she had never said anything of the sort and hastened to distance herself from Weyrich's remarks.

"I do not want to be associated with any kind of accusations or innuendo that there is any illegality going on," Moore said. However, she welcomed Weyrich's endorsement, saying it reflected her broad base of support.

Weyrich, a longtime Republican activist and vocal conservative, said he put aside philosophical differences and the objections of party members to back Moore because Herrity favors Hazel's interests over those of Fairfax County.

Although Herrity does not appear to have benefited financially from his position, "You've got to look at the longer-range picture," Weyrich said. "A lot of people get taken care of. I can't offer evidence or anything of the sort. It's just instinct," he added.

In a statement issued by his campaign, Herrity said Moore owes him, his family and the people of Fairfax an apology "for engaging in such irresponsible tactics." Herrity spokeswoman Connie Bedell condemned Weyrich's suggestion that the chairman might reap some future financial gain from Hazel as "slanderous" and "outrageous."

A spokesman for Hazel, a lawyer who has amassed a fortune developing vast tracts of land in Fairfax in the last two decades, echoed Bedell's sentiments. Weyrich's statements were "unfounded as he himself admits and . . . scurrilous," Robert C. Kelly said.

Weyrich told reporters at the morning news conference that two policy controversies illustrated Herrity's partiality toward Hazel. He said Herrity opposed a plan that would extend light rail mass transit through the Dulles International Airport corridor with private funding. Weyrich, who headed the federal task force that advanced the plan, said it would spur growth and generate competition for Hazel's developments elsewhere in the county.

Herrity repeated his position yesterday that Weyrich's light rail plan would go forward "over my dead body" because it would invite a crush of development into the Dulles corridor. Weyrich's plan involves rezoning to allow for higher density development.

Weyrich also cited Herrity's support for a 1985 property swap between Hazel and the county. Under the deal, the county gave Hazel's development firm a 36-acre parcel on the east side of Stringfellow Road near the Fair Oaks Mall in return for 44 acres of parkland west of Stringfellow. Hazel also promised to spend $1 million on improvements to the parkland. Moore was the only member of the Board of Supervisors who voted against the 1985 deal.

Hazel, a principal in Hazel/Peterson Cos. and of the law firm of Hazel, Beckhorn, Hanes, Thomas & Fiske, stands to realize a huge profit if the 36-acre parcel is rezoned for commercial use, Weyrich said.

According to Hazel's spokesman, Hazel has not sought a rezoning for the land near Fair Oaks Mall, and the playing fields the firm promised the county will be ready for use in the spring.