Roberto Mancini branded referee Antonio Damato and his fellow officials "a disaster" after watching Inter lose 3-0 to AC Milan in Serie A.
Mancini was sent to the stands by Damato early in the second half at San Siro for fiercely protesting a decision not to award a penalty after Inter debutant Eder was challenged by opposing goalkeeper Gianluigi Donnarumma.
The Inter boss also appeared to raise his middle finger to Milan fans as he left the dug-outs.
Milan were ultimately convincing winners thanks to goals from Alex, Carlos Bacca and M'Baye Niang, while Mauro Icardi missed a penalty for Inter, and Mancini could scarcely contain his anger post-match.
"I do not know what to say on the foul [Donnarumma's challenge on Eder]. You see that Damato not know the rule," Mancini told Premium Sport.
"There was a sending-off in the first half that was not given. I would understand if the rules are the same for everyone. The referee has been a disaster, and his team.
"Congratulations to them that they have won, but it is not the right result."
Inter have now lost back-to-back matches 3-0, following their midweek capitulation against Juventus in the Coppa Italia.
"Our defence must once again be as strong as it was at the beginning and have the support of all the players," said Mancini.
Asked about the reasons for him being sent from the dug-outs, the Italian said: "I did not say anything offensive, but they are so particular."