MANCHESTER UNITED rebel Wayne Rooney has come clean over his determination to leave Old Trafford and blamed his decision on the club’s lack of ambition.

Rooney questioned United’s ability to continue to win trophies and insisted he had only refused to sign a new contract after failing to receive reassurances they would bring in world-class signings.

The England star also denied suggestions from Sir Alex Ferguson that he had failed to show the club respect, after the manager broke his silence on the conflict with his most important player on Tuesday.

Rooney’s admission paves the way for a sensational January transfer window switch to arch-rivals Manchester City, who are thought to be leading the chase.

Injured Rooney missed last night’s clash with Bursaspor and some bookmakers were offering even money that the 24-year-old had played his last game for the club.

“I met with [United chief executive] David Gill last week and he did not give me any of the assurances I was seeking about the future squad,” Rooney said in a statement released just hours before the game.

“I then told him that I would not be signing a new contract. I was interested to hear what Sir Alex had to say yesterday and surprised by some of it.

“It is absolutely true, as he said, that my agent and I have had a number of meetings with the club about a new contract. During those meetings in August I asked for assurances about the continued ability of the club to attract the top players in the world.

“I have never had anything but complete respect for MUFC. How could I not have done given its fantastic history and especially the last six years in which I have been lucky to play a part?

“For me its all about winning trophies – as the club has always done under Sir Alex. Because of that I think the questions I was asking were justified.” Rooney, whose relationship with Ferguson is said to have deteriorated beyond repair, said he would always be grateful to the Scot.

“Despite recent difficulties, I know I will always owe Sir Alex Ferguson a huge debt,” he added.

“He is a great manager and mentor who has helped and supported me from the day he signed me from Everton when I was only 18. For Manchester United’s sake I wish he could go on forever because he’s a one off and a genius.”