Real Madrid's former president Ramon Calderon has hinted that Cristiano Ronaldo could be set for a sensational return to Manchester United after growing disillusioned with life at the Santiago Bernabeu.

Calderon was instrumental in bringing Ronaldo from Old Trafford to the Spanish capital, and now believes that the Portuguese star is fed up with current president Florentino Perez's transfer policies and is willing to move away from the club he joined from United in 2009.

"My impression is he is fed up with the policy of the current president," Calderon told talkSPORT.

"When he came [to Real Madrid] with [Arjen] Robben he thought he would be a good colleague for him in the team [but then he was sold]."

"Two years ago it was [Gonzalo] Higuain sold and he didn't like that. Last year he thought it was a mistake to let [Mesut] Ozil leave and the last straw was selling Xabi Alonso and Angel di Maria this summer," the former Real president explained.

"When I signed him in 2008, I remember he said he was grateful to Manchester United. He had a marvellous time there, he likes everything. It is a really great club," Calderon added.

Ronaldo did question Perez's transfer decisions earlier in the summer following the sale of Angel di Maria to United and then Xabi Alonso's departure to join Champions League rivals Bayern Munich.

The Portuguese international also hinted that he could return to United to end his career. He also added that he could move back to Portugal or remain at Real Madrid, which he considers as the 'best club in the world'.

"I could say that I would like to end my career at Real Madrid, which is the best club in the world," Ronaldo said.

"Or Manchester United because I have a special history with the club. Or maybe at Sporting, who gave me my foundation," the European player of the year added.