Federal officials in Baltimore, stepping into a housing dispute that has caused an uproar here in Howard County's "new town," yesterday ordered the new owner of the Tilbury Woods apartments to halt a planned conversion of the units to all-adult housing.

The intervention by the U.S. Department of Housing and Urban Development marked the first time in Maryland that the federal agency has overturned an all-adult policy at an entire housing project, said Kenneth F. Hannon, the chief of loan management in HUD's Baltimore office.

Hannon said that the Boston-based Krupp Company's plan to convert the 300-unit Tilbury Woods complex violated the terms of the 40-year, federally-insured mortage that Krupp asssumed when it acquired the property earlier this year.

That $2 million mortgage agreement prohibits discrimination against tenants with families, Hannon said.

Hannon said that he had conferred with Krupp vice president Jack Davenport by telephone yesterday and received the real estate firm's promise that it would not seek the eviction of any leaseholders merely because they had children.

Some tenants who had received eviction notices had claimed they were being singled out for eviction because of their families. Earlier, Krupp officials had said that families would be allowed to renew their leases for at least the next year.

Davenport could not be reached for comment.

The HUD action capped several weeks of public debate over the Krupp Co. plan. Several community leaders, including County Council members and a director of a coalition of human service agencies, contended that an all-adult policy would violate Howard's antidiscrimination law, which prohibits discrimination on the basis of age.