Ronaldo has yet to reveal his plans, although Madrid have repeatedly attempted to lure him to the Bernabeu in a long, public courtship.

The capital club's conduct has angered United, who reported Madrid to world governing body FIFA over what they considered to be attempts to unsettle the player.

FIFA refused to take any formal action, however, and Calderon is adamant his club have an amiable relationship with their English rivals and would not do anything to upset that.

"Manchester United are friends of ours," he told Spanish newspaper Marca.

"Madrid cannot do anything (to get Ronaldo) if Manchester do not want to sell their player."

However, Calderon could not resist adding that if United could be persuaded to sell Ronaldo, he is confident a deal would be reached.

"If the player wants to come here and United are ready to sell, then Real Madrid will show their interest in signing him because he is a great player," he added.

"If this were the case, then I am sure that we would be able to reach a deal."