Arsenal have released an official statement following the events on Thursday night that saw disruption outside and inside the Emirates stadium during and before their Europa League tie with FC Köln.
The match itself was postponed an hour due to the disturbances caused by supporters of the Bundesliga outfit, and while five arrests have been made as a result of the events, Arsenal stress that "fan safety was always paramount".
The statement reads on the club's official website: "We worked in full consultation with police and UEFA officials on the night and in advance of the game and had taken extensive steps in advance to prevent tickets being sold to visiting supporters.
"This included a number of measures including ensuring no tickets were sold via general sale and that no red memberships purchased after the draw were able to be used to get tickets in the home end for this match.
"We also worked with our colleagues at Cologne to stop supporters travelling without match tickets.
"The 3,000 tickets issued to Cologne fans was in line with competition rules but it is clear many more visiting fans arrived, causing significant congestion and disturbance outside the stadium before kick-off. Many tickets were sold through touts and this is very disappointing.
"We have launched a full review into the circumstances surrounding the game and will ensure any lessons that can be learned are used in the future.
After the match, when asked if UEFA should take action, Gunners boss Arsene Wenger replied (as quoted by TalkSPORT): "They are the only master to analyse the facts of what happened. They will certainly make an inquiry to see what happened, for sure.
"They [Köln fans] were very clever. I don't know how they managed to infiltrate our fans and get everywhere but they did that very well. I don't know if they went through Arsenal membership, on the internet... they did very well.
"We live in a society of 100 per cent security and I thought they would never take a gamble to play this game when I saw the images around the stadium. But I must say our supporters as well dealt well with the situation as well and there was no aggravation."
Despite going 1-0 down to a spectacular early goal from Jhon Cordoba, efforts from Sead Kolasinac, Alexis Sanchez and Hector Bellerin gave the Gunners a 3-1 victory, taking all the points in their opening game of the competition.