Sir Alex Ferguson refused to answer a question on the Alan Wiley situation at a press conference on Tuesday.
The Manchester United boss faced the media for the first time since being charged with improper conduct by the Football Association for allegedly questioning referee Wiley's fitness.
Ferguson was at an obligatory event in Russia ahead of Wednesday night's Champions League Group B tie against CSKA Moscow when he was asked to comment on the charge.
"Silly question gets no answer," the Scot said. "I'm not answering it.
"We're at a press conference for a game tomorrow. We're here to talk about that."
At that point Ferguson decided to end the press conference, which had already run for 22 minutes, and left the room.