The D.C. government yesterday filed suit against the city's Board of Elections and Ethics in an attempt to block placement on the Nov. 6 ballot of an initiative that, if approved, would require the city to provide "adequate overnight shelter" for thousands of homeless people.

"It is with a good deal of reluctance and a good deal of reservation that we take this step," said city administrator Thomas M. Downs, one of several key city officials who appeared at a press conference yesterday to announce that the lawsuit had been filed at the D.C. Superior Court.

"One of the chief problems with the initiative itself is it provides only for a form of warehousing," Downs said.

Initiative 17, sponsored by the Community for Creative Non-Violence, an activist organization that works in support of homeless persons, would require the District to provide shelter that is "accessible, safe and sanitary and has an atmosphere of reasonable dignity." Persons who enter the District "for the express purpose of obtaining free shelter" would be excluded from the initiative's coverage.

City officials said yesterday that as many as 15,000 homeless people could seek shelter if the referendum passed. They added that the provision would require the financially beleaguered District to spend about $60 million to build massive new shelters.

That amount, officials said, is nearly 10 times more than is currently available for the homeless and would divert funds from other badly needed services.

Officials also said establishment of shelters by the District would discourage the private sector, including church groups, from helping the homeless.

Downs said that city shelters would "create a unique magnet on the East Coast" that would attract homeless people from other jurisdictions.

Homelessness, he added, "is a complex set of circumstances" that requires medical, psychiatric and job counseling services, not merely overnight housing.

Valerie K. Burden, a member of the D.C. Board of Elections and Ethics named in the lawsuit, declined to comment.

Stephen O'Neil, a member of the Community for Creative Non-Violence who submitted the initiative, said city officials had "distorted all facts, logic and reason" and oppose the initiative "for political reasons, not legal ones," a charge officials strenuously denied.

Corporation Counsel Inez Smith Reid said the city's challenge is based on a recent D.C. Court of Appeals decision on a proposed initiative on unemployment compensation. The court said unemployment compensation was an improper subject for a referendum because implementation would require the appropriation of funds, an act reserved for the City Council.

The Coalition for the Homeless, a group of churches and private community organizations, opposed the initiative for many of the same reasons city officials cited yesterday.