Cristiano Ronaldo
Real Madrid's Cristiano Ronaldo celebrates after scoring a goal against Levante during their Spanish first division football match at Santiago Bernabeu stadium in Madrid, on 6 April, 2013Reuters

Portuguese star Cristiano Ronaldo is likely to return to his old English club - Manchester United - after leaving for Spanish giants Real Madrid four years ago. 

The 28-year-old star, who has two more years at Santiago Bernabeu under his current contract, has reportedly rejected a new contract deal with the Real Madrid, throwing up possibility of returning to his old club.

Cristiano Ronaldo is said to be unhappy with the way Real Madrid president Florentino Perez has been treating him of late and wants to leave the club though Perez recently said that he was confident the Portuguese striker would end his career at Bernabeu.

"I think that Cristiano will end his professional career at Real Madrid," said Perez. "I don't know whether the Madridistas are very concerned about the contract renewal of Cristiano. He still has a contract for two more years," the Metro quoted Perez as saying. 

However, Spanish publication AS has reported that Manchester United is ready to pay up to £50million for Ronaldo's return.

New coach David Moyes' attacking line-up would be strengthened if they sign Ronaldo even if England star Wayne Rooney leaves the club as rumoured.

It is reported that Rooney, 27, who has been sidelined ever since Robin van Persie joined Manchester United, has reportedly placed a transfer request to Sir Alex Ferguson. He could well leave Old Trafford after nine years if the new coach David Moyes fails to convince him in the coming weeks.

Several clubs like Arsenal, Chelsea, Paris Saint-Germain and Bayern Munich have reportedly shown interest in signing the England striker if Manchester United give green signal for his exit.