The Portuguese midfielder became the most expensive football player in history when he made the Ã‚Â£80 million switch from Old Trafford to the Santiago BernabÃƒÂ©u last June.
The 25-year-old, who has already scored nine goals in 12 appearances for Real Madrid, is also said to have generated interest from both Barcelona and Inter Milan.
CalderÃƒÂ³n, 58, who resigned as Real Madrid President last month following allegations of vote-rigging for the confirmation for the financial budget at the club, stated that a deal had already been struck for Ronaldo’s transfer long before it was officially announced.
“Cristiano came to an agreement with Manchester United for a transfer to Real on December 8, 2008,” he told Eurosport.
“During last summer there was no negotiation, everything was already concluded. The player accepted a clause of Ã¢â€šÂ¬30 million in case the transfer failed, but Inter and Barcelona also entered the race,” he continued.
“The Red Devils were willing to resolve that clause for those two clubs and not sell to Real. Everyone knows there is not a good relationship between the two clubs [Manchester United and Real Madrid].
“However, the situation was eventually resolved by Cristiano himself, who remained faithful to [his deal with] Real Madrid,” he added.
Real Madrid travel to Xerez on Saturday evening as they attempt to close the five-point gap separating them from Barcelona at the top of the La Liga table.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news