A D.C. City Council bill that is intended to prohibit new foreign chanceries in residential neighborhoods apparently would block the long-planned construction of embassy offices by France and Italy, the city's top legal officer has declared.

Louis P. Robbins, acting D.C. corporation counsel, reached the conclusion in an informal opinion prepared this week for the mayor's legislative office. Robbins ruled the council lacks legal power to enact the bill.

The bill, recommended for council enactment byits committee on housing and community development would bar the future rezoning of any property now zoned as residential for use as a chancery site.

The French government has applied to develop an 8-acre part of the Archbold estate on Reservoir Road NW at the western edge of Georgetown. The Italian government has filed a similar application for the 27-acre former Firenze estate on Brandywine Street NW adjoining Rock Creek Park.

"It . . . appears that the (proposed) bill would operate to abrogate the Zoning Commission approval" of these chanceries since the final change of zoning has not taken place, Robbins said.

Council member Polly Shackleton (R-Ward 3), chief sponsor of the bill, said she would support an amendment to permit the French and Italian projects to proceed.

"I think a commitment has been made . . . whether one favoured them or not," she said.

A news account published yesterday in The Washington Post erroneously reported the basic finding of Robbins' legal opinion. Robbins ruled that the City Council lacks legal power to enact the restrictive bill.

In a related development yesterday, a delegation from the Dupont Circle Coalition urged Mayor Walter E. Washington to oppose a Zoning Commission action this week to permit more chanceries on the Massachusetts Avenue Embassy Row.

The mayor declined to intervene, but said he agrees with the basic idea that chanceries should not squeeze residences out of an area.