Hargreaves joined United in 2007 from Bayern Munich but only started 27 Barclays Premier League games in four seasons.
The Daily Mail reports Ferguson accuses Hargreaves of not having "nearly enough determination" and claimed he opted "for the easy choice" in training.
"When I signed him there was something about him I didn't like," added Ferguson.
"It turned out to be a disaster."
Ferguson also revealed in his book that United briefly thought about suing Hargreaves in the wake of his claims about his treatment.
He also commented on reports that Hargreaves may one day work for the FA.
"That's one of the things that's wrong with our game," he said.
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