Advocate for the homeless Mitch Snyder demanded yesterday that Mayor Marion Barry's administration withdraw and apologize for a letter warning D.C. public housing tenants that they face eviction for having unauthorized persons living in their units.

Department of Housing and Community Development Director Madeline M. Petty sent letters Tuesday to 4,000 residents in 22 properties, including 14 that house senior citizens, announcing an "all-out effort to evict those persons who are in violation of their lease agreement." The letter said any unauthorized persons must leave the units by June 30.

In a letter to Barry, Snyder yesterday called the housing department's letter "insulting, inaccurate, illegal and unconscionable." Snyder said tenants would be encouraged to seek legal action if Barry does not order the housing department to withdraw and apologize for the letter by Monday.

"No government official should write in such terms to anyone, least of all the vulnerable public housing population of senior citizens, handicapped people, and poor struggling families with young children," Snyder wrote.

Snyder also contended that the city's letter is illegal because it does not inform tenants of their administrative procedural rights, including the right to an administrative grievance hearing with the agency.

Barry's press secretary said that the mayor had no comment on Snyder's letter but would hold a news conference on public housing today.

In a statement issued on Wednesday, the Barry administration moved to clarify the new housing policy by saying that tenants would be given time to add names to their leases and to correct other lease violations. Although eviction procedures would be initiated if violations were not corrected, the clarification said no timetable had been established for such evictions.

As an additional clarification, Barry said his report on the condition of public housing, which estimated that 40,000 people are living illegally in public housing, was in error and, in fact, there are about 3,000 to 4,000 illegal residents.

But housing advocacy groups are not satisfied by those clarifications, saying that they will not reach tenants who received the housing department's letter.

"It is a deliberately terrifying letter," said Florence Roisman, a lawyer with the National Housing Law Project. "The only thing that is good enough to correct the letter is another letter to the same people."

City Council member Charlene Drew Jarvis (D-Ward 4), head of the council's housing committee, said the council may take action to have letters hand-delivered to the 4,000 tenants through tenant resident councils.

"It seems to me it [the letter] generates needless alarm on behalf of many families," said Jarvis. "It is really a letter designed for the guilty and doesn't distinguish from the guilty those living in conformity."

There are 60,000 legal public housing tenants living in 11,769 units, housing officials said. The department plans to send more notices warning that violations of lease agreements must be corrected.