Roberto Di Matteo has responded to Sir Alex Ferguson by saying negative comments about Chelsea are "nothing new" while implicitly criticising the Manchester United manager for speaking so publicly on such incidents.
Earlier on Friday, Ferguson offered his views on the situation, saying: "I don't believe Mark Clattenburg would make any comments like that. I refuse to believe it."
However, Di Matteo, who has tended to be evasive in his Chelsea press conferences, responded in surprisingly strident manner.
"As I said, it is a free country and everybody can say what they want," he said. "He likes to talk about other clubs. We tend not to. I'll leave it up to him. It doesn't really affect me too much to be honest.
"We take into consideration what other people say and use it as a motivational tool for ourselves."
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.
Asked whether Ferguson's comments were "unhelpful", Di Matteo responded: "It's always a tricky question, whether it's helpful or not.
"Ultimately, we have to try and block as much as we can, block this situation out and just focus and channel our energy on what matters to us as players and coaching staff when we get onto the pitch on a Saturday afternoon."
Otherwise, Di Matteo could not get into the specifics of Ferguson's comment.
"I think the investigation will clarify that so we cannot comment on it," he said. "We do not want to prejudice any investigation. We will wait and see what comes out. I can't comment."
It was a frequent refrain in his Friday press conference. Questioned as to whether referees would alter their attitude as regards Chelsea, Di Matteo replied: "I hope not. I believe that they won't. That's my belief.
"We have faith in the referees. They are people that are under a lot of pressure. They are human beings, like everyone else. You have to try your best but sometimes mistakes can happen."