The Supreme Court yesterday lifted a stay that had blocked the return home of a 9-year-old Zimbabwean boy allegedly beaten by his father, a diplomat who has been expelled from his post in New York.

The court's action, ending a month-long diplomatic and legal battle, permits the State Department to turn Terence Karamba over to Zimbabwe for placement in a foster home there.

The State Department has said it will make the transfer after a psychiatrist hired by the department certifies that the severely traumatized boy is psychologically prepared for the journey. An attorney involved in the case said he expects that process to take two or three weeks.

State Department spokesman Charles E. Redman said return of the boy "may be a long process." U.S. officials said that the boy would be returned to Harare in the company of Zimbabwean officials and that the U.S. Embassy has retained a law firm to help him and his two younger sisters.

The battle over Terence Karamba began Dec. 11, when New York City child-welfare officials took him into custody as an abused child and determined that his father had beaten him.

The State Department ordered the father -- Floyd Karamba, an administrative attache at Zimbabwe's U.N. mission -- to leave the country because of the alleged child abuse.

U.S. officials said international law, however, required that the boy be turned over to Zimbabwean officials. New York officials challenged that but lost in lower federal courts, which said the State Department could pick up the boy anytime after noon last Saturday.

That order was temporarily stayed by Supreme Court Justice Harry A. Blackmun until the full court could review the matter yesterday. Without comment or recorded dissent, the court removed the stay in a two-sentence order.

Joseph R. Carrieri, an attorney for the foster care agency, said that, despite the court's action, the agency is confident that it will have time to prepare him psychologically for his return home.

The State Department's psychiatrist and the agency's psychologist have been working closely to prepare the boy, Carrieri said. The boy's mother has left the country, he said, but the agency may ask the Zimbabwean government to consider "having the foster family or a social worker come over from Zimbabwe and get to know him" before the boy is returned.

Zimbabwe's foreign minister had threatened retaliation against the United States unless the child's "abduction" ended immediately. But Zimbabwean officials have made no further public statements, and U.S. officials said no formal requests have been made for the boy's immediate transfer to Zimbabwean authorities.