Philippe Clement questioned the VAR process which ruled out a penalty claim in Rangers’ 2-1 defeat by Celtic at Parkhead.
Leading through a Paulo Bernardo goal in the first half, Celtic full-back Alistair Johnston appeared to handle the ball inside his own penalty area under pressure from Abdallah Sima.
The VAR check for handball came to nothing but it later emerged that Sima had been offside in the build-up.
Kyogo Furuhashi added a second just after the break before Rangers defender Leon Balogun was shown a straight red by referee Nick Walsh for denying Daizen Maeda a clear goalscoring opportunity.
Gers skipper James Tavernier curled in a wonderful free-kick in the 88th minute to make it an anxious ending for Celtic, who moved eight points clear of their Old Firm rivals at the top of the table having played two games more.
It was a first defeat for the Belgian in 17 games as Rangers boss and he was left perplexed.
“My biggest frustration isn’t Cyriel Dessers missing a chance because (Erling) Haaland and (Kylian) Mbappe miss chances like that,” said Clement, who claims he was handed a yellow card during the game “for reacting too hard on a ball that was clearly ours given to the other side”.
“My biggest frustration is that if there’s a clear handball, I don’t understand why it’s not a penalty given.
“It’s a clear thing so I’m curious about it.
“There was no communication towards me. And if the communication is that Sima is offside, I’m not a referee but there should have been a clear signal from VAR for offside.
“Then everyone knows the decision. There was no communication at that moment.
“Otherwise, the signal of the referee is not correct. So there’s been a mistake and it’s clear for everyone to see.
“I also make mistakes but it’s an expensive one today.”
Clement was not displeased with the way his side performed in a stadium which had home fans only amid an allocation dispute between the two clubs.
He said: “The match was a good promotion for Scottish football with two teams who wanted to win, attacked and created chances.
“I need to look at my side and I’m happy with what they showed me today.
“We had more shots than Celtic but we didn’t take our moments.
“They were more efficient on the day and when games are in the balance like that, you can lose them.
“It could have been a draw, we could have won it. But the circumstances weren’t on our side.
“My team reacted in the second half, even after a world-class goal to make it 2-0. It’s a very good goal and you can’t do too many things about it.
“But we never stopped, even with 10 men. We kept going and created enough chances to score our goal and others. We went until the end and everyone here became nervous.”