Mark Clattenburg is ready to formally deny allegations he used "inappropriate language" towards Chelsea stars John Obi Mikel and Juan Mata. Press Association Sport understands referee Clattenburg has been shocked and angered at being accused by the European champions of using comments that have been interpreted as racist remarks during their defeat to Manchester United on Sunday. The Football Association launched an investigation on Monday after Chelsea made an official complaint against the 37-year-old, who has vowed to co-operate fully with their enquiries and is understood to be determined to clear his name. That would also apply should the police choose to launch their own probe after confirming on Monday night they were "considering" what they described as a "complaint" from the Society of Black Lawyers. The FA had yet to interview Clattenburg on Tuesday morning but are expected to do so, possibly after requesting a written account from him about what took place during Sunday's Barclays Premier League game at Stamford Bridge. Clattenburg has already filed what is known as an 'extraordinary incident report', which is understood to mainly deal with a meeting which is alleged to have taken place in the referees' room after full-time. Sources told Press Association Sport that Chelsea manager Roberto Di Matteo, assistant manager Eddie Newton and chief executive Ron Gourlay were all present as Mikel angrily accused Clattenburg of abusing him. The referee, his assistants and fourth official are understood to have been stunned by the claims, with Michael McDonough, Simon Long and Michael Jones denying hearing anything of that nature over the officials' microphone link-up. Clattenburg's fellow professional referees are understood to be as shocked and angered as their colleague over the allegations against him and were rallying around him.