UEFA has opened disciplinary proceedings following the crowd trouble which overshadowed Thursday night’s Europa League match between Arsenal and Cologne at the Emirates Stadium.

The Group H tie, in which Arsenal eventually ran out as 3-1 winners, was delayed by an hour as ticketless Cologne fans looked to gain entry to the ground.

The visitors were issued with 3,000 tickets, but around 20,000 Cologne fans are believed to have made the journey to London. There were clearly thousands of away supporters sitting among Arsenal fans, causing a security risk.

Five arrests were made over the course of the evening and Arsenal issued a statement on Friday insisting the safety of supporters was the main concern at the time as the Premier League club “launched a full review” of the events.

Both clubs now face disciplinary charges from governing body UEFA, which include crowd disturbances, setting off fireworks, throwing of objects and acts of damage by Cologne fans, while Arsenal face a probe for “stairways blocked in away supporter sector”.

UEFA will deal with the case on September 21, the governing body confirmed in a statement on Friday.