Muhammad Ali's image as a force for social change in the 1960s who became a goodwill ambassador in infirm later life, is shredded in a new book.

"Seldom has a public figure of such superficial depth been more wrongly perceived - by the right and the left," says Mark Kram, who for 11 years as a sports writer covered what many believe to be the finest boxing career ever seen.

"He was not about the anti-war movement; that was peripheral, a college-kid issue that he tolerated and used. He was not about the counterculture and certainly not women's rights."

What Ali, now 59, was about was playing the role of the malleable dupe of the Nation of Islam movement, bedding numerous women and searching the skies for UFOs, says Kram in his book, Ghosts of Manila. What he is about now is acting as a mute front man, a Parkinson's sufferer, for advertisers and investors.

Kram, who gives Ali his due for achievements in the ring, says that he became tired of reading hagiographies that represented the former heavyweight champion as second only to Martin Luther King among the heroes of the civil rights movement.

"Ali was no more a social force than Frank Sinatra," he writes. "The politically fashionable clung to his racial invective as if it were the wisdom of a seer. Today, such are the times, he would be looked upon as a contaminant, a chronic user of hate language and a sexual profligate."

Kram has been described on a black radio talk show as a racist while Lonnie Ali, the boxer's fourth wife and spokeswoman, says the writer is a liar.

Certainly, the Kram book delivers a vision far removed from that of recent biographies of Ali, who received a medal from the former president, Bill Clinton, for humanitarian works and lit the flame at the Atlanta Olympics in 1996.

King of the World, by David Remnick, the Pulitzer prize-winning editor of the New Yorker magazine, identified Ali as "a new kind of black man" who altered forever racial politics and popular culture.

Thomas Hauser, Ali's official biographer, said: "Ali in the 1960s stood as a beacon of hope for oppressed people all over the world. Every time he looked in the mirror and uttered the phrase 'I'm so pretty', he was saying 'black is beautiful' before it became fashionable."

Ali became a widely derided figure, lost his title, was unable to box and risked jail after refusing to join the US army in 1967. But Kram says that he was manipulated by Elijah Muhammad, leader of the Nation of Islam, rather than acting as an independent, principled opponent of the war in Vietnam.

"Had he not become a Muslim, chances are he would have remained unfit for duty after failing two previous tests that put him near the moronic level."

The fulcrum of Kram's book is Ali's bout with Joe Frazier in Manila in 1975. Ghosts of Manila includes many of Ali's other fights and Kram's accounts of their meetings over the years.

A disparate cast of characters flits across the pages, including Clint Eastwood, Orson Welles, Deng Xiaping, Elvis Presley, John Wayne, Idi Amin, the Beatles, Sammy Davis Jr and Gamal Nasser.

Women, too, are there: two before one fight, five before another. "Our women should be honoured," Ali said during his years away from boxing, "but they should understand their inferiority. Man gotta look down on women and women up to men whether they standing up or laying down. I don't take any sass."

"Ali would be the first to tell you that he never wanted to be deified, to be a god," said his wife, Lonnie. "A person's perception is their reality. Whatever Mark Kram perceives, or thinks he perceives, that's his reality. If the rest of society perceives Muhammad as a cultural icon, so be it."