A confrontation between developer John O. Antonelli and Dupont Circle residents is being played out on three stages - in hearings before the Board of Zoning Adjustment (BZA), in negotiations with the State Historic Preservation Officer and in meetings of the Zoning Commission.

Antonelli, stepson of millionaire parking lot magnate Dominic F. Antonelli Jr., wants to build a 90-foot-high office building behind and attached to three Victorian townhouses he owns in the 1700 block of N Street NW.

"Those buildings are coming down if I can't built a 90-foot office building behind them," Antonelli told members of civic groups who attended a negotiating session chaired by the State Historic Preservation Officer last week. A six-month delay in demolition on the three townhouses, which are included in the Dupont Circle Historic District, expires Nov. 28, after which Antonelli will be free to demolish the buildings.

If he cannot build the office-building addition, Antonelli said at the negotiating session, he will demolish the townhouses and put up a 90-foot-high apartment building.

James Fahey, the District zoning administrator, said that Antonelli has applied for a building permit for the apartment building, but that it is uncertain whether the permit will be granted.

Antonelli's attorney, Norman M. Glasgow, said he was not aware of any problems with the building permit application and that he expects the permit to be issued.

Neighborhood groups say they want to preserve the three townhouses, which were built by Cairo Hotel architect T. F. Schneider. They also say they want to stop, or at least reduce the size of, the proposed office building. The residents claim the structure would add to the already considerable traffic problems on the narrow street and detract from its low-rise ambiance. They claim that Antonelli is using demolition of the houses as a threat to try to get community support for the zoning variances he needs for the proposed office building.

Guy Martin, Antonelli's architect, told the BZA at a recent hearing that the proposed eight-story office building would be dark red brick to match the townhouses and St. Matthew's Cathedral, which is behind the Antonelli property. He said the addition would be in a style compatible with the Victorian townhouses, whose facades would be restored.

John Keats, whose law firm owns four townhouses on the block, said, "We previously opposed the plan, but after much soul searching and after reviewing the plans with Mr. Antonelli, we decided to support the application. We're aware of the alternatives."

But three property owners on the block, represented by attorney Nick Addams, who also has an office on the block, continue to oppose the plan. So do the Dupont Circle Citizens Association and Don't Tear It Down, a D.C. preservation group.

Addams accused the BZA of advancing the case on its agenda to accommodate Antonelli, an accusation vehemently denied by BZA staff director, Steven Sher. Sher pointed to several cases filed after Antonelli's that appeared on the agenda the same day.

The Zoning Commission is conducting a series of public hearings to consider rezoning much of the Dupont Circle area. The Dupont Coalition, composed of seven neighborhood groups, has proposed that the 1700 block of N Street be rezoned to permit only 65-foot-high buildings. For that reason, those who oppose the Antonelli plan say they hope the BZA will not rule on the case until after the Zoning Commission has acted on the matter. It is uncertain which body will act first, but neither body is expected to rule on the matter before Nov. 28, the date Antonelli will be free to raze the houses.

At last week's negotiating session, members of community groups asked Antonelli to delay any demolition plans at least until after the BZA ruling is announced, but the developer refused to commit himself. When asked to reduce the size of the proposed addition, Antonelli replied that he was willing to absorb the extra cost involved in saving the townhouses - about $200,000 - but that reducing the size of the building would make the project economically unfeasible.

Some community representatives say they would accept the Antonelli project if the office addition could be smaller, especially if Antonelli shows good faith by closing a parking lot behind the houses.

Last spring, Antonelli applied for BZA permission to operate a parking lot behind the townhouses. Neighbors who appeared at a hearing on the matter last June said Antonelli was already operating an illegal parking lot behind the houses. The neighborhood residents were supported by the city Department of Transportation. In September, the BZA voted to deny the application, and a written order denying the right to operate a parking lot on the site was issued Oct. 24.

A sign now on the parking lot reads, "Accessory Parking for Tenants Only," which Antonelli's lawyer says is a legal use of the property.

Zoning administrator Fahey said in a telephone interview that he has determined, after an inspection last week, that such a use is not in accordance with city zoning regulations. He said he had forwarded the matter to the District corporation counsel's office "for enforcement."

At last week's negotiating session, both sides agreed on only one thing - that additional negotiating sessions would be futile.

"I have paid all I'm going to pay," said Antonelli. "This group has come in here and laid down a lot of 'I wants.' I don't think they want to save the buildings . . . I am trying to save the buildings. I only ask in return that I be allowed to put an office building in the rear that won't be detrimental to anyone. Addams and his group are determined to stop me at any cost. I hate to tear the buildings down, but Nov. 28 they're coming down if I have to do it."

"Antonelli is only interested in making maximum dollar on this project as opposed to reasonable dollar," said Addams at the negotiating session."Mr. Antonelli wants to blackmail us with idea of tearing them (the townhouses) down. He's saying that if we don't accede to his desires he'll tear them down."