Harry Belafonte was slapped with a libel suit by his half-brother yesterday over the autobiography the singer-turned-liberal activist released last year. Raymond Wright claims Belafonte’s book, “My Song: A Memoir,” contains “a cluster of libels” intended to “incite media dislike of Wright and dissuade the media from publishing Wright’s work.” Wright’s rambling, self-written suit, filed in Manhattan federal court, says his older sibling “accuses Wright of anti-Israel denunciations and implies Wright is anti-Semitic.” It says they’ve been estranged ever since a 1991 Post column by Fred Dicker, which reported how Wright urged then-Gov. Mario Cuomo to stop funding the “scandal-scarred” Martin Luther King Jr. Institute “created by Cuomo at Belafonte’s request” and divert its $1.5 million budget to homeless programs. Wright made the request after his and Belafonte’s mom, Melvina Belafonte Wright, died alone and sick after living in a Manhattan shelter. Belafonte’s rep didn’t return a call for comment.