Uefa has sacked one of its officials after admittingits new anti-racism strategy was not properly enforced during the incident involving Yaya Touré that means CSKA Moscow will have to play their next Champions League game in a partly closed ground.

The inquiry into last week's problems at the Khimki Arena has cleared the Romanian referee Ovidiu Hategan of any wrongdoing, having established that he did inform the fourth official there should be a public announcement aimed at the CSKA fans who had been racially abusing Touré.

The investigation, requested by the Uefa president, Michel Platini, discovered that the breakdown came when the message was relayed by the fourth official to the venue director, also employed by the governing body.

Uefa has not named the director but a statement confirmed he had "been relieved of his duties" while CSKA's reduced capacity for their next home fixture in the competition, against Bayern Munich on 27 November, is intended to serve as a warning to the Russian club.

CSKA, City's opponents again in Manchester on Tuesday, have vehemently denied the allegations but will be made to play behind closed doors if there is a second offence, with a warning from Uefa that "the fight against racist conduct has been stepped up a level resulting in more severe sanctions."

Hategan, like all Uefa referees, had been instructed to implement a "three-step protocol" if any players report racial abuse, starting off with halting the game to make a public announcement. That did not happen in Moscow despite Uefa's confirmation that Touré did approach the referee, after a free-kick was awarded in the 54th minute, to complain that he could hear the crowd making monkey chants.

"The referee and the additional assistant referee standing on that side of the field witnessed the inappropriate behaviour of a small number of supporters," Uefa's statement said."The referee immediately asked the fourth official to request an announcement to be made to the public. The venue director [the Uefa officer in charge of football operations], who had not heard the chanting himself, did not activate the procedure. As the chanting had ceased, the referee decided to resume the game with the free-kick.

" The conclusion of the investigation is therefore that the referee had correctly triggered the first step of the procedure by requesting the stadium announcement. The venue director acted inappropriately, though in good faith, so causing the failure."