Rooney's current Old Trafford contract expires in 2012
Striker Wayne Rooney is not for sale at any price, Manchester United chief executive David Gill told BBC Sport.
Rooney is in brilliant form with 21 goals this season which could trigger an offer from Europe, with Barcelona and Real Madrid said to be interested.
But Gill told BBC 5 live Sportsweek: "Unless Alex agreed to it, we would not accept an offer, regardless of the value, for a player we want to keep."
Gill said they had a 35m Euro bid for France striker Karim Benzema refused.
United manager Sir Alex Ferguson had been tracking the talented 22-year-old for months but saw his offer rejected by Lyon, who accepted a 41m Euro bid by Spanish giants Real Madrid in July 2009.
"We didn't get Benzema but we did offer 35m Euros," said Gill.
If I went to (joint board chairman) Joel Glazer and said 'Alex wants a particular player, can we have the money?' The answer would be an unequivocal yes
Man Utd chief executive David Gill
"It was just one phone call to the States saying we would like to make an offer for him 35m Euros and they said 'fine'. We did it, but he went to Real for something like over 40m Euros.
"But Alex has gone on record saying that was too much."
Gill also alleviated fears that United's owners, the Glazer family, would sell Old Trafford or the club's Carrington training ground.
A prospectus circulated to potential investors prior to the club's £504m bond issue last week suggested Carrington could be sold to a holding company controlled by the Glazer family and leased back to the club.
But Gill said: "I am 100% convinced that will never happen under Glazer family ownership. The sale and leaseback opportunity within the bond document is done for financial and tax planning. Manchester United Limited continue to have complete control of Carrington."
The bond issue allowed the club to pay off nearly all their outstanding bank debts of £509m, although the debts of the club's parent firm, Red Football Joint Venture, rose to £716.5m in the year to June 2009.
While the club now faces an annual interest bill of £45m a year, Gill said the club has no financial reasons to sell their prized assets, including Rooney, who is enjoying his best form for United since his £25m move from Everton in 2004.
"Wayne has a contract through until 2012," said Gill. "He has gone on record to say he wants to stay and we want him to stay.
"I'm sure that will be addressed in the close season. We hope that would be the case as we want to put him on a new, long-term contract. He's 24 and got the best years of his life ahead of him.
"Very few players, particularly UK-based players, want to leave Manchester United."
And Gill's pledge to keep hold of Rooney, was backed up by the player himself who spoke of his desire to remain at United.
"This is my club and I'm very happy here," said Rooney.
"My family live 30 minutes away. I'm perfectly happy and there is no reason to play my football anywhere else. Manchester United are the biggest club in the world."
Gill stressed that United's debts of £500m are a "misconception" because the club has about £140m in cash available, over half of which was generated by Cristiano Ronaldo's world record £80m transfer from United to Real Madrid last summer.
And he confirmed manager Sir Alex Ferguson can spend all £80m on new players, should he wish to expand the squad.
"I'm sure if he needed that money, it would be spent," said Gill, who oversaw the arrival of defender Chris Smalling from Fulham for about £7m on Thursday.
"If I went to (joint board chairman) Joel Glazer and said 'Alex wants a particular player, can we have the money?' The answer would be an unequivocal yes. They have demonstrated it (with Benzema).
"From my own personal perspective, we have no doubt that they (the Glazers) would support whatever we require.
"They will only get value back by ensuring the team continues to be successful, continues to attract exciting players and continues to produce results off the pitch.
"The Glazer family bought (American football team) the Tampa Bay Buccaneers in 1995 and 15 years later, they still own that - they are in it for the long-term."
While Gill reiterated the Glazers' commitment to the club, supporters are planning a 10-minute boycott of the Champions League last 16 match against AC Milan on 10 March.
Concerned by the debt the club has accumulated under the Glazers, a number of fans plan to enter the ground 10 minutes after kick-off to expose empty seats at the ground with millions of people watching around the world.
But Gill believes any protest would be counterproductive on a night when United will be bidding to reach the Champions League quarter-finals.
"I would appeal to the fans to be sensible and get behind the team," he added.
"We are a very well-run club and, given what's happening at other clubs, people should be proud of what's happening at Manchester United.
"It (the protest) serves no purpose and it won't change a thing. It will a tough game and we can't afford for the fans not to be there. Let's not have ridiculous protests of that nature, in my opinion."
However, Manchester United Supporters' Trust chief executive Duncan Drasdo said he was unsatisfied with Gill's assurances, adding that they left many questions unanswered.
"I think there was a lot of window dressing there," Drasdo told BBC Sport.
"The key point here is, how much money are the Glazers putting into Manchester United versus how much they are taking out. The answer is they are putting none in and taking a hell of a lot out.
"The key to the bond issue is that it has opened the door to Manchester United's vault and now the Glazers can drive in with a fork-lift truck and load up cash.
"They could take up to £130m out of the club in the first year and up to £500m in the seven years of the bond issue.
"They are leaching huge amounts of money from our football club - money that fans are paying through huge increases in ticket prices.
"How much money are the Glazers taking out of Manchester United, wasting on interest fess, banking fees, hedging of interest rates.
"How much are they taking out for their personal companies in management fees? That would be the interesting question I would like answered."
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