A furious Mikel Arteta described Arsenal’s defeat against Inter Milan as “very, very difficult to accept” – and said his side should have been awarded a penalty after Mikel Merino was “punched” in the head.

Arsenal fell behind on the stroke of half-time when Inter were awarded a contentious penalty after Merino was adjudged to have handled the ball in the area.

Merino might count himself unfortunate given he could do little to get out of the way of Mehdi Taremi’s flick-on. Hakan Calhanoglu converted the ensuing spot-kick to send the Gunners to their second defeat in four days.

Earlier in the opening period, Merino had his own penalty claim when Inter goalkeeper Yann Sommer delivered an unintentional right hook to his head.

Asked for his reaction to the hosts’ spot-kick, Arteta said: “I don’t understand. There is no danger at all. You cannot react because the ball is very close.

“We were told at the start of the season that wasn’t a penalty. That was clear. Today it was a different story. But OK. They decide that is a penalty.

“But if that is a penalty then the one on Mikel Merino where he punches him in the head has to be a penalty, 1,000 per cent. These are the margins in this game and it’s very, very difficult to accept.

“I am extremely frustrated because these are two decisions that marked the course of the game. Unfortunately, there is nothing we can do. We have to accept it and move on.”