The Real Madrid player has been making noises to suggest he is unsettled at the Bernabeu, an issue understood to relate to falling down the highest-earners pecking order.
The Ballon d'Or holder is paid around £288,000-a-week but has slipped behind former team-mate Wayne Rooney and recent arrivals at Manchester United, Radamel Falcao and Angel Di Maria.
With Ronaldo expressing discontent, rumours of a return to the Premier League have surfaced. The player himself said in a recent interview: "I love Manchester.
"Everyone knows that — I have said it many times. Manchester is in my heart. I left many good friends there, the supporters are amazing and I wish I can come back one day."
It's understood Real Madrid want to put an end to the speculation with the Evening Standard reporting that the Champions League holders have decided to issue a hands-off statement.
The Evening Standard also quote a Spanish insider as saying: "This is all about money. Cristiano considers himself to be one of the world’s greatest players and doesn’t want to be paid less than anyone else, no matter who they play for.
"But Madrid are in no mood to let him go and will almost certainly end up giving him whatever he wants. He’s too important for them to let go."
Part of the £80m deal that saw the Portugal international leave Old Trafford in 2009 sees Manchester United with first-option on Ronaldo should he become available.
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