An Arsenal spokesman said:
"Stadium security is of the highest importance and Arsenal Football Club feel there is ample stewarding around the dugout area,"
"However, the club does recognise that some exchanges which takes place can be of an aggressive nature, and there was an incident this afternoon where one supporter was ejected.
"As a club we do expect a certain level of behaviour.
"There is also CCTV which monitors the area which our stadium management crew do review in detail after games, and if necessary the club will take further action."