Jose Mourinho has exchanged bitter words with his Portuguese compatriot Cristiano Ronaldo over claims that Manchester United get special treatment from referees.

Mourinho insisted last weekend there was a new rule in football that United should never concede a spot-kick and Chelsea should never win one. But when Ronaldo replied by insisting the Chelsea manager "never recognises when he is wrong", Mourinho suggested he would be lying if he denied United received special treatment.

Mourinho said on Portuguese television: "A player that wants to be the best in the world needs to behave well, to keep quiet and to have sufficient honesty and maturity to verify that against the facts that I have shown, there is no argument on his part.

"If he says that it is false that Manchester United have conceded penalties that were not given, it's lies. And if he is a liar he will never reach the highest level that he desires in football."

Ronaldo, however, is exasperated by Mourinho's non-stop digs at Chelsea's rivals.

In the space of seven days Mourinho has not only claimed United get special treatment but also taunted Liverpool by insisting they are not a big club and claimed that Chelsea should have won a spot-kick against Rafael Benitez's side - even though the offence clearly happened outside the penalty box.

Now Ronaldo has finally snapped and decided to speak out about his countryman. The United winger said: "The whole world knows how Mourinho is. He always has to say something to gain attention, especially when he is not happy with the work of his players. He never recognises when he is wrong."