Manchester United boss Sir Alex Ferguson says he is surprised Jose Mourinho has not been called to account for some of his recent remarks.
Ferguson was upset by Mourinho's remarks about Ronaldo
The Chelsea manager has stated that United have received favourable refereeing decisions this season.
Ferguson said: "Mourinho seems to be on some sort of personal crusade. I am surprised no action has been taken.
"It's calculated. We have four games to go now. If we get a penalty against us, Mourinho wins that war. That is wrong."
He went on: "It is a rant all the time now. I don't think it is fair to the game."
Last weekend Mourinho insisted that there was a "new rule" in football which meant United could not concede a penalty and Chelsea could not win one.
Everyone is entitled to have an opinion. That doesn't mean to say they are liars
He was referring to spot-kicks both Sheffield United and Middlesbrough felt they should have been given at Old Trafford and a penalty he thought Chelsea should have had at Newcastle.
That provoked United winger Cristiano Ronaldo to claim that Mourinho "does not know how to admit his own failures".
The Chelsea boss hit back: "If Ronaldo says it is a lie penalties were not given against United, then he is lying."
Mourinho's comments about his fellow Portuguese in turn upset Ferguson, who said on Friday: "Everyone is entitled to have a comment or opinion. That doesn't mean to say they are liars."
And Ferguson added: "Mourinho is on about us changing the regulations. I would like to know who is doing it? Is it us? The FA? The Premier League? Uefa?
"I really feel he has been let off lightly with those comments.
"The biggest fear for us is that by citing the fact we are not allowed to get penalties at Old Trafford, it puts a terrible pressure on the referees."
Ferguson also pointed to several decisions that he felt had gone against his own club.
"Does he remember the goal Paul Scholes had disallowed for offside when we played against Porto in the European Cup?" said the United boss.
"We didn't like it and we complained. But we didn't go to war on it.
"Or should he be pointing to the fact Tottenham were forced to play on a Easter Saturday morning, a day and a half after their previous game, to allow Chelsea to rest before their European tie?
"We have to play Manchester City at 12.45 on a Saturday after a European tie in Milan next Wednesday. Is that fair? We don't think so but we are not going to start accusing the Premier League of carving things up with Chelsea."
United are three points ahead of Chelsea in the Premiership with four games left, with the two sides meeting at Stamford Bridge on 9 May.
They will also face each other in the FA Cup final and both clubs are in the semi-finals of the Champions League.