Manchester United manager Sir Alex Ferguson has backed referee Mark Clattenburg after Chelsea made allegations that the official used "inappropriate language".
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Both the Metropolitan Police and the FA are currently investigating claims made against Clattenburg by Premier League leaders Chelsea in the wake of last Sunday's clash with United at Stamford Bridge.
Chelsea have lodged an official complaint for what they believe was a racist insult directed at Nigeria midfielder John Obi Mikel, although a second allegation involving Spain playmaker Juan Mata has since been dropped. ESPN understands Clattenburg maintains his innocence.
Ferguson - whose United side played at the Bridge for a second time in a week on Wednesday when Chelsea won their Capital One Cup tie 5-4 in extra time - said he finds the allegation difficult to credit.
"I don't believe Mark Clattenburg would make any comments like that," Ferguson said in his pre-match press conference ahead of Saturday's home clash against Arsenal. "I refuse to believe it.
"If we see the game today as it was 25 years ago it's completely changed. I played myself and I know that the banter which went on between referees and players 25 years ago is different to today.
"I've never had a player come to me in the last 15 years and say a referee swore in a game - ever."
The affair took a further controversial turn after pictures emerged of a man in the stands at Wednesday's game appearing to make a 'monkey' gesture in the direction of United striker Danny Welbeck. Both the Metropolitan Police and Chelsea are investigating the incident.
Arsene Wenger added to the dissenting voices, the Arsenal manager choosing to criticise Chelsea's decision to go public with their grievances.
"My opinion is just that I prefer, when I didn't behave well, that I have an explanation with the referee at the end of the game or on another day, (rather) than going public with little proof," Wenger said. "I'm not a great believer in making these stories public.
"I have not always behaved very well, they are very heated situations but I am a deep supporter of doing that internally. One of the great things in sport, especially in England, is that when the battle is on, you can sort out the problems you had internally. If it becomes a sport to make the lawyers rich, I am not a fan of it.
"One of the great things in sport as well is tolerance, forgiveness and explanation internally and I think it should stay like that. It can happen that a referee doesn't behave well, I do not say they are angels, but it is always better to sort it out in the room."