Former Manchester United manager Alex Ferguson launched his new autobiography yesterday, lifting the lid on his relationships with stars such as David Beckham, Cristiano Ronaldo, Roy Keane and Wayne Rooney.

Ferguson said Beckham became too obsessed with fame in the latter years of his Old Trafford career and reiterated his claim Rooney asked to leave the club at the end of last season.

He confirmed that Keane, his long-serving captain, was asked to leave the club after lashing out at several of his younger teammates in an interview with in-house television channel MUTV that was never broadcast.

He also said he was offered the England manager's job in 1999 and 2001, but turned it down.

"There was no way I could contemplate that. It wasn't a bed of nails I was ever tempted to lie on," he said in "My Autobiography."

Ferguson, 71, stepped down as United manager after a 26-and-a-half-year tenure in which he won 13 Premier League titles, two Champions League crowns, five FA Cups and four League Cups.

The Scot was forthright about several superstars.

He described Beckham as "the only player I managed who chose to be famous, who made it his mission to be known outside the game."

Ferguson said he decided to sell Beckham to Real Madrid after an incident following an FA Cup loss at home to Arsenal in February 2003 when he accidentally kicked a boot into the midfielder's face during a post-match argument.

"The next day the story was in the press," Ferguson said.

"It was in those days that I told the board David had to go. The minute a Manchester United player thought he was bigger than the manager, he had to go."

Ferguson described Ronaldo, who left United for Madrid in 2009, as "the most gifted player I managed" and said watching him play for the first time was "the biggest surge of excitement... I experienced in football management."

The Scot disclosed a conversation he had with Rooney when he asked to leave the club in 2010.

Ferguson said Rooney was worried about United's ambition and urged him to sign Mesut Ozil.

"My reply was that it was none of his business... I told him it was his job to play and perform."