Arsene Wenger took offence with a "scandalous" refereeing performance after Arsenal's humbling Champions League defeat to Bayern Munich, but he insists the club remains in great shape despite the 10-2 aggregate loss.

The Gunners crashed out at the last-16 stage for the seventh successive year as the Bundesliga champions repeated their 5-1 first-leg victory at the Emirates Stadium.

Theo Walcott put Arsenal ahead on the night before Xabi Alonso's challenge on the winger in the penalty area went unpunished by the Greek match officials.

The game then swung in Bayern's favour when Laurent Koscielny was shown a straight red card for a tackle on Robert Lewandowski, opening the door for the visitors, who scored five goals in the final 35 minutes.

"We put Bayern under pressure and were unlucky because it was a 100 per cent penalty at 1-0 in the first half against Walcott," Wenger said in his post-match press conference.

"In the second half, the referee killed the game. After that, it was very different, but the referee I think was very powerful for Bayern tonight.

"Lewandowski, it was not only not a penalty, he was offside and on top of that he gives us a red card. That killed us completely.

"Overall, I must say that Bayern are a good side but today they must also say thank you to the decisions of the referee in the second half.

"I am angry and frustrated and at the moment, because we are in a difficult period, even more so.

"It's absolutely unexplainable and scandalous what happened really - that the guy behind the line gives the penalty and on top of that the red card after he had given the yellow.

"We have to take it on the chin and I have to stand up. I will take a lot of criticism but it doesn't change my mind. In the game, you have to deal with these situations but it doesn't make them right.

"I felt that we played very well and the referee has let us down. It was more the decisions of the referee that killed the game.

"It's irresponsible from the referee. At the end of the day, that is the reason for tonight's result."

The humiliating defeat, Arsenal's heaviest at the Emirates, only added to the discontent surrounding Wenger's position at Arsenal, which reached new heights before kick-off as fans participated in anti-Wenger protests.

Asked whether it was his last Champions League as Arsenal manager, the Frenchman added: "I don't know.

"You are always worried for headlines but I speak about football not about my future.

Wenger was similarly dismissive of suggestions that the defeat was his most disappointing during his managerial career in European competition.

"I don't feel so because we knew before the game it was difficult to qualify after the first game," he said.

"But we wanted as a minimum to go home and feel like we dealt with the situation with pride and commitment. And we did.

"At the end of the night, the result will not highlight the quality of our performance, which is very disappointing."