Roberto Di Matteo hits back at Sir Alex Ferguson, saying Manchester United are favoured by referees

Roberto Di Matteo yesterday reacted to Sir Alex Ferguson's defence of Mark Clattenburg by accusing Manchester United of being more favoured by referees than any other Premier League club. The Chelsea manager, speaking after two tempestuous games with United in four days, also criticised Ferguson for having an opinion on affairs that do not concern him.

Asked about decisions in United's controversial league defeats of Liverpool and Chelsea, and whether he was worried by perceived favouritism towards United, Di Matteo said: "I think there is a lot of evidence for that".

Di Matteo did not go so far as to suggest there is a conspiracy but the Italian does see a pattern. "There are some feelings in general but I don't think [referees] do that with a purpose," he said. "It is just part of their decision-making and it seems to go in one direction." Asked whether it was merely a function of United's status, Di Matteo disagreed. "I don't know. We are a big club as well. Liverpool are too. Does it even itself out? I don't know."

Speaking after Ferguson had questioned Chelsea's accusation against the referee Clattenburg, Di Matteo insisted he did not approve of managers talking about other clubs, and that Chelsea would use it to motivate themselves.

"It is a free county and everybody can say what they want," Di Matteo said. "He likes to talk about other clubs, we tend not to, I'll leave it up to him. We take into consideration what other people say and use it as a motivational tool for ourselves."

Agreeing that Ferguson's comments were "unhelpful", Di Matteo said the United manager made a habit of it. "I have to say that it happened in the past as well. I think there is a lot of respect between your colleagues, the managers, in general. And everybody has a different approach. Some people talk about other clubs and clubs' issues, and some don't."

Despite the criticism Chelsea have faced recently, including over the Clattenburg complaint, Di Matteo reaffirmed his feeling that they have done the right thing. "We believe we did what was right," he said. "I cannot say more than that because of the investigation."

Chelsea would not comment on the supporter photographed making seemingly racist gestures on Wednesday.

For all the controversy, Chelsea are still top of the Premier League, in the Capital One Cup quarter-finals and alive in the Champions League. Di Matteo is confident this is not being overshadowed. "I think a few people have started to recognise that," he said. "Over time more people will."

After criticism over Chelsea's style of play last year, Di Matteo said he was used to dealing with outsiders commenting on his club. "People comment about the way we play, the way we deal with issues," he said.

"It's nothing new. It's been happening for years. I'm not playing a victim here – every team that is successful will be talked about. It's nothing surprising for us that all the people talk about Chelsea.

"We're going to continue on our road. We respect other people's views and comments, but believe in what we do. We believe we behave correctly and will try to continue like that. We have an objective in front of us and are going to continue to work for that. If other people have different objectives or opinions it won't influence us."

Di Matteo tried to play down suggestions that his job had been made much harder by recent events. "It makes it a little more complex," he said, "but ultimately I'm enjoying training and working with the players and preparing for games."

Juan Mata and David Luiz are doubts for today's game at Swansea. Branislav Ivanovic is likely to play at centre-back.