José Mourinho has been fined £25,000 and warned as to his future conduct by the Football Association after claiming a “campaign” was being mounted against Chelsea in the wake of last month’s draw at Southampton, though the manager has avoided a touchline ban for the comments.

An FA hearing was convened ahead of the second leg of Chelsea’s Capital One Cup semi-final against Liverpool on Tuesday with Mourinho found guilty in absentia of “improper conduct” for his comments about referees in December. The commission did conclude that the Portuguese, who had been fined on three separate occasions last season for his antics on the touchline, had not implied bias.

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“Following an independent regulatory commission hearing, José Mourinho has been fined £25,000 after he was found to have breached FA rules in relation to media comments,” confirmed the FA in a statement.

“The Chelsea manager denied that comments he made after the game against Southampton on 28 December 2014 constituted improper conduct in that they alleged and/or implied bias on the part of a referee or referees, and/or brought the game into disrepute.

“The independent regulatory commission found the comments were a breach of FA Rule E3 in that they were improper and brought the game into disrepute. The commission did not, however, find that the comments implied bias on the part of a referee or referees. Mr Mourinho, who had requested a non-personal hearing, was also warned as to his future conduct.”

Chelsea are awaiting the full written reasoning with interest from the FA before they will comment on the sanction.

The Chelsea manager had been incensed that Cesc Fàbregas had been denied a penalty at St Mary’s following a foul by Matt Targett, with the Spain international booked by the referee, Anthony Taylor, for diving. The caution was awarded after several other perceived instances of simulation had been highlighted over previous weeks – involving Diego Costa, Wilian, Gary Cahill and Branislav Ivanovic – with Mourinho moved to suggest a media campaign was being instigated against his team, with the inference that it was potentially influencing match officials.

“That’s a campaign, that’s a clear campaign,” he said at the time. “People, pundits, commentators, coaches from other teams, they react with Chelsea in a way they don’t react to other teams. They put lots of pressure on the referee and the referee makes a mistake like this. We lose two points, Fàbregas earns a yellow card. In other countries where I worked before, tomorrow in the sports papers it would be a front-page scandal because it is a scandal.

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“I think it is a scandal because it is not a small penalty – it is a penalty like Big Ben. In this country – and I am happy with that, more than happy with that – we will just say that it was a big mistake with a big influence in the result. I am happy that it is this way, with respect for the referee. He made a big mistake like I make, like the players make sometimes.”

Chelsea will learn later today whether Diego Costa faces a three-match ban for violent conduct – which would potentially rule him out of Saturday’s visit of Manchester City to Stamford Bridge – over his clashes with Emre Can and Martin Skrtel in Tuesday’s victory over Liverpool, with an independent FA commission to sit on Friday to hear any potential appeal. The FA’s governance department reviewed footage of the two incidents on Wednesday morning and will now ask the referee, Michael Oliver, whether or not he witnessed the incidents the governing body feel deserve further attention.

Should Oliver confirm that he did not see either of the incidents at the time – the sense is the first clash with Can is more likely to provoke punishment than the second with Skrtel – the FA would then ask the referee what punishment he would have considered necessary had he witnessed them first-hand. That is according to Football League rules, as it was their competition. In the equivalent disciplinary cases in the Premier League, there is a separate panel for deciding the punishment.

The FA will either issue a charge or decide there is no case to answer by the close of business on Wednesday under their fast-track system. If a charge is forthcoming, Costa and Chelsea would have until the end of the day to decide whether they are to accept or request a personal hearing. An independent commission would be convened on Friday to hear the case and would rule before Saturday’s top-of-the-table clash with City.