WASHINGTON — Breaking his 16-year public silence on his bitter confirmation hearings, Supreme Court Justice Clarence Thomas says Anita Hill was a mediocre employee who was used by political opponents to make claims she had been sexually harassed.

Justice Thomas writes about Ms. Hill, his former employee in two government agencies, and the allegations that nearly derailed his nomination to the high court in 1991 in his autobiography, “My Grandfather’s Son.”

The book goes on sale Monday.

He writes with indignation of the nationally televised hearings that he memorably called a “high-tech lynching.” A child of the segregated South, Justice Thomas says he was being pursued “not by bigots in white robes but by left-wing zealots draped in flowing sanctimony.”

Powerful interest groups were out to stop him at all costs and chose “the age-old blunt instrument of accusing a black man of sexual misconduct,” he writes.

Ms. Hill, who is also black, had worked for Justice Thomas at the Education Department and the Equal Employment Opportunity Commission. She first made her allegations after Justice Thomas had been nominated to the high court, 10 years after she began working for him and only after she was contacted by congressional investigators.

In the book, Justice Thomas describes Ms. Hill as touchy and apt to overreact, not someone who would wait a decade to level a charge of harassment. She had complained to Justice Thomas only about his refusal to promote her, the justice says.

“Her work at EEOC had been mediocre,” he writes.

In 1991, Justice Thomas adamantly denied Ms. Hill’s accusations that he made inappropriate sexual remarks, including references to pornographic movies. Justice Thomas says he did talk about X-rated movies while at Yale Law School, adding that so did many other young people in the 1970s.

Justice Thomas says now that he was “one of the least likely candidates imaginable” for a charge of harassment, having made clear his desire to run an agency staffed mainly by minorities and women as professionally as any other.

Justice Thomas, 59, acknowledges that three other former EEOC employees backed Hill’s version of events, but he says they either had been fired or had left the agency on bad terms.

Ms. Hill, a professor at Brandeis University, declined tonight to comment on the book.

The 289-page book, for which Justice Thomas has been paid more than $1 million by publisher HarperCollins, is an account of his up-from-poverty story from his first home in tiny Pinpoint, Ga., through his swearing-in as a justice at the age of 43.

He recounts the brief period in which he lived with his mother and brother in a one-room apartment in Savannah. The building had no indoor plumbing, and one of Justice Thomas’ chores was emptying the chamber pot. He spent most of his childhood living with his grandparents and attending Catholic school.

Justice Thomas is the second black justice in the nation’s history, having taken the seat of the first, Thurgood Marshall.

Justice Thomas does not discuss his colleagues or his work on the court.

He does, however, trace his rightward political shift from a protesting college student at Holy Cross and a George McGovern supporter in 1972 to an appointee of Presidents Reagan and George H.W. Bush.

In the roughly one-third of the book spent recounting his nomination to the court, Justice Thomas says his opponents were obsessed with the issue of abortion and determined to stop him because they believed he would oppose abortion rights.

As a justice, Justice Thomas has called for overturning the landmark Roe v. Wade decision, which would leave states free to deal with abortion as they wish.

But at the time of his nomination, Justice Thomas told senators he had never discussed the case. In the book, he describes himself in the years before he joined the court as a lazy libertarian, with mixed feelings about abortion and uncomfortable telling others what to do.

Within a few months of his confirmation, however, the court was faced with a case that offered the prospect of overruling Roe v. Wade. By then, he says in a footnote, he had ample time to study the issue and concluded that Roe was wrongly decided in 1973.