Wayne Rooney has told Manchester United he wants to quit the club, leaving manager Alex Ferguson "shocked and bemused" and paving the way for a bidding war to start for the England striker.

Ferguson stunned reporters on Tuesday by confirming media speculation that the 24-year-old wanted out, saying he had been told on August 14 that the forward, whose contract runs out in 2012, would not be signing a new deal.

"We are as bemused as anyone can be. We can't quite understand why he would want to leave," Ferguson told a news conference where the "Wayne issue" had to wait until after the half-hearted questions about Wednesday's Champions League match.

He added Rooney would miss that Group C match against Bursaspor with the ankle injury that has been at the centre of much of the newspaper furore.

A United spokeswoman said he had been taken off the field on a stretcher towards the end of training on Tuesday, having earlier been seen laughing and joking with his team-mates in the session as he kept warm in black hat and gloves.

Ferguson said he had been told of Rooney's decision by United chief executive David Gill.

"It was a shock," Ferguson said. "I couldn't believe it because in other discussions as early as March he intimated that he wanted to stay, he wanted to sign a life contract, he was happy at the club, he was at the best club in the world.

"I had a meeting with him. He intimated to me in his own way that he wanted away.

"I told him, 'The only thing I want from you, Wayne is to honour the club's position and traditions and behave like a proper professional and we'll try to see it through.'

"There was an offer there, it never got into financial discussion, but I know David was prepared to offer him a contract that would be difficult to better elsewhere," he added.

With Rooney barely off the back or front pages in recent months, following revelations about his private life, Ferguson later told MUTV that he had doubts over whether the player had taken notice of his plea that he did not want "any nonsense".

He said the door was still open for a deal to be reached but Rooney could have plenty more offers to consider if any of the reports linking him to the likes of United's big-spending neighbours Manchester City and Real Madrid come to fruition.

Glancing at prepared notes, Ferguson spoke for several minutes uninterrupted on the subject before folding up his piece of paper and leaving without taking questions on his statement.

He denied falling out with Rooney but the pair are clearly at odds over whether the striker is injured or not with Ferguson speaking at length about what he called the "mystery area" of his ankle problem.

The manager has been resting Rooney because of the injury, which he picked up in a Champions League game against Rangers last month, but after playing for England earlier this month Rooney denied being injured.

"He said he wasn't injured, that was disappointing as we knew well he was carrying an injury, he went for a scan that showed a minor defect and he had treatment," said Ferguson.

Ferguson, who bought the then 18-year-old Rooney for 25.6 million ($40.40 million) from Everton six years ago, said the club had done everything it could for him -- including giving advice on his finances and his private life.

"You look after players and that creates a tremendous loyalty," said Ferguson.

"We don't understand why he would want to leave. No one can deny it's one of the most successful (clubs) in British football ... (it has) a fantastic history, a great stadium, great training arrangements.

"I can't answer any questions about why he's doing it -- the player is adamant he wants to leave," he added.

Rooney helped United to Premier League titles in 2007, 2008 and 2009 and the Champions League in 2008.

He was in brilliant form for his most of last season but after injuring his ankle in a Champions League game at the end of March he did not score another goal and was way below his best form on his return and for England in the World Cup.