An American civil rights lawyer hired to breathe new life into chess legend Bobby Fischer's efforts to fight deportation to the United States accused U.S. officials on Monday of "grotesque" abuse of their powers and threatened to take the case to the Supreme Court.

Richard Vattuone accused Washington of persecuting Fischer for his political views, refusing to observe due process in the revocation of his U.S. passport and ignoring objections over the legality of its moves to have him deported.

U.S. Embassy officials denied Fischer was being treated unfairly.