The Health and Human Services Department yesterday proposed regulations intended to encourage hospitals built with federal aid to continue, after being purchased by profit-making corporations, offering free care to the poor.

The rules would waive a requirement that such hospitals pay back part or all of their federal Hill-Burton grant if they are sold to profit-making companies. Under the waiver, the money could instead be put into a trust fund devoted to health care for poor patients.

"Thousands of hospitals, nursing homes and other health-care facilities have received Hill-Burton assistance on the condition that they provide a specified minimum amount of free care to the poor . . . , " HHS Secretary Margaret M. Heckler said in announcing the regulations.

"Today, as many of these facilities are changing ownership, we need a new approach to help assure continued free care for indigent patients under Hill-Burton," she said.

About 3,000 hospitals and 2,000 other facilities, such as nursing homes, still have Hill-Burton obligations to provide free care to the poor. About $450 million in free care is provided each year because of the requirements, an HHS spokesman said.

But if such a hospital is sold to an investor-owned company, he said, HHS is required under current regulations to get part of the money back -- and the hospital in turn is relieved of its legal obligation to provide free care.