Arsenal have revealed the “number of measures” they took in attempt to stop Koln fans sneaking into the home end at the Emirates prior to Thursday night’s Europa League chaos and pledged that lessons would be learned from what happened.

The Gunners ran out 3-1 winners in the Group H opener, which was delayed by an hour and saw as many as 20,000 Koln fans making the journey from western Germany despite only 3,000 tickets being made available, five of whom were arrested by Met Police.

That meant many attempted to enter without tickets or with tickets for the Arsenal sections, where it soon became clear ahead of kick-off that plenty had succeeded.

Arsene Wenger suggested Koln fans may have done this by subscribing to Arsenal membership online but the Gunners have revealed they closed this option off to fans prior to the Europa League draw being made last month.

In a statement, Arsenal said: “Following last night's Uefa Europa League match with Koln we would like to stress that fan safety was always our paramount concern and informed all decisions made.

“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 Koln to stop supporters travelling without match tickets.

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“The 3,000 tickets issued to Koln 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.