UEFA has opened disciplinary proceedings against Arsenal and Cologne following incidents at the Europa League match at The Emirates on Thursday.
European football's governing body has charged Arsenal with blocking stairways in the away supporters section of the stadium during the Group H fixture against their German opponents.
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It has charged Cologne on four counts - crowd disturbances; the setting off of fireworks; throwing objects; and acts of damage.
Cologne supporters - whose side were competing in European competition for the first time in 25 years - were allocated 3,000 tickets for the match but another 17,000 fans are believed to have made their way to the ground.
Congestion and outside the ground led to kick-off being delayed by one hour until 9:05pm, with Arsene Wenger's side eventually winning 3-1.
Arsenal have already begun an investigation into the incidents, which led to five people being arrested following crowd disturbances.
A police statement issued after the game said: "No reports of any significant incidents. Five people have been arrested on suspicion of public order offences."