D.C. zoning officials last week blocked plans by the Washington Hilton to expand into residential neighborhoods near the hotel at Connecticut Avenue and Columbia Road NW.

At the same time, zoning officials voted to allow the Saudi Arabian government to expand embassy offices into a residential neighborhood, while rejecting a similar request from the nearby Iranian embassy.

The hotel chain has made offers to buy three adjacent apartment buildings on Columbia Road -- the Schuyler Arms, the Wyoming and the Oakland -- and has proposed that the city close Adams Community School, which is next to the hotel at 19th and California streets NW, and sell it to the Hilton.

"The hotel has been looking for ways to expand, and Washington is short about 6,000 hotel rooms," Whayne Quin, attorney for the hotel said this week.

Residents and city officials have opposed expansion of the 1,168-room hotel, primarily because it would eliminate 227 apartment units from the city's already-dwindling rental supply.

Hotels closed or converted more than 1,000 apartment units here last year," said Ann Hughes Hargrove, chairman of the Adams-Morgan Advisory Neighborhood Commission.

In action designed to prevent the Hilton expansion, the D.C. Zoning Commission approved an emergency, 120-day order prohibiting the conversion or razing of any buildings for hotel purposes in R-5 zones (basically rowhouse and apartment neighborhoods). Apparently, only the Washington Hilton is affected by the order.

Under present zoning laws, hotels are permitted in R-5 zones as a matter of right. This spring, however, the commission held hearings on proposed zoning changes that would limit hotels to certain sections of the city and ban them in the future from residential neighborhoods. The commission is expected to vote on the proposals at its September meeting.

In the Saudi Arabian case, the D.C. Board of Zoning Adjustment (BZA) -- which can grant exceptions and variances to zoning regulations in hardship cases -- agreed to allow the embassy to install a chancery in a house at 2929 Massachusetts Ave., in the Cleveland Park area, which is in the diplomatic overlay zone along Massachusetts Avenue.

Diplomatic overlay zones were created by the city's Zoning Commission last year. Under the regulations, which created specific diplomatic districts, chanceries may be permitted in areas which "overlay" residential zones, providing the BZA determines the chanceries would be compatible with the neighborhood.

Under the Saudi plan, the house on Massachusetts will be used for offices, with construction of 25-car parking lot behind the house. The plan was vigorously opposed by area residents at a hearing last January. The BZA decided to approve the Saudi request, however, after visiting the site last month.

Thomas Corcoran Jr., who with his father. Thomas G. Corcoran, has represented residents opposed to the plan, said this week he plans to appeal the BZA decision to the D.C. Court of Appeals. Corcoran Jr. said he will seek a stay, pending the appeal, to prevent gardens behind the house from being torn up to make way for the parking lot.

This "will bring lots of traffic, office lighting and noise" to Cleveland Park, Corcoran said, and "every embassy in the neighborhood will be tempted to acquire the house next door . . . and turn it into a chancery."

Corcoran said he will argue that the chancery is not compatible with the neighborhood and that diplomatic overlay zones violate the 1964 Federal Chancery Act, which prohibits chanceries in residential neighborhoods.

Attorneys for the Saudi government had argued before the BZA that the proposed use of the house met all zoning requirements and that they planned to spend more than $2 million to restore the 1917 brick mansion to its former elegance.

In a similar case, the Iranian government had requested a zoning change to permit business use of a 1920s mansion adjacent to the Iranian embassy at Massachusetts Avenue and 30th Street NW. The mansion, which is about 100 yards from the Saudi house on Massachusetts, is on the edge of, but not within, the diplomatic overlay zone.

The house, renovated last summer, abuts the embassy grounds but has its entrance at 2500 30th St. NW. Iran proposed the change during the Shah's reign, but the new government is consolidating its Washington offices and had hoped to use the third floor of the mansion as office space for 14 persons.

Even though zoning commissioners said they were concerned about Iran's "vague" plans for the house, they indicated that Iran can reapply immediately for the zoning change. Attorney Sylvan Marshall, who represented Iranian interests in the zoning matter, said theis week he expects the Iranian government will do so.

Residents have opposed the zoning change because "the neighborhood doesn't want what used to be a house and a home and a neighbor to become a business," Thomas G. Corcoran told the commission during hearings last March.

In other action last week, the Zoning Commission approved the site plan for a 268-townhouse community on the 42-acre Archbold estate. The development, to be known as Hillandale, would be on River Road across from Georgetown University Hospital.

The project developers, headed by Dallas Cowboy owner Clinton Murchison, agreed to move one cluster of townhouses further from the Glover-Archbold Park. The developers already have agreed with local citizen groups to limit traffic to a single entrance on 39th Street NW, just south of S Street NW, and to increase buffer zone landscaping to shield existing homes. The project required commission approval because it was designed under a Planned Unit Development (PUD) process.