Arsenal have promised a “full review” into disorder at The Emirates last night after 20,000 FK Koln fans descended on the stadium for their team’s Europa League game.

Islington Gazette: Police with dogs keep watch the FC Koln fans. Picture: Nick Potts/PA WirePolice with dogs keep watch the FC Koln fans. Picture: Nick Potts/PA Wire (Image: PA Wire)

Five arrests were made after riot police were sent in to deal with crowds trying to storm the ground.

Kick-off was delayed for an hour, but when the match eventually started at 9.05pm it became clear hordes of away fans were sitting with the Arsenal supporters, causing fights to break out.

“I don’t know how they managed to infiltrate our fans and get everywhere but they did that very well,” Arsenal manager Arsene Wenger said after the 3-1 win. “I don’t know if they went through Arsenal membership, on the internet... they did very well.”

Scotland Yard said the majority of supporters had left the stadium and the area by midnight and said there were “no reports of any significant incidents”.

Islington Gazette: FC Koln fans outside The White Swan pub in Upper Street before the game. Picture: Nick Potts/PA WireFC Koln fans outside The White Swan pub in Upper Street before the game. Picture: Nick Potts/PA Wire (Image: PA Wire)

An Arsenal club statement said fan safety was always their priority and laid some of the blame with touts who had sold tickets to the away fans, adding they had worked with the German club beforehand to stop supporters travelling without tickets.

The club added: “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.

“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.”

Islington Gazette: FC Koln fans outside Higbury and Islington underground station. Picture: Nick Potts/PA WireFC Koln fans outside Higbury and Islington underground station. Picture: Nick Potts/PA Wire (Image: PA Wire)

Earlier the fans had gathered in the West End and Highbury Corner on their way to the match.

Arsenal supporter and political editor of ITV, Robert Peston, tweeted before the game: “These Cologne fans are a disgrace. Nazi salutes. Peeing in doorsteps. My European solidarity being tested.”

Highbury locals also said there were “hundreds of young men shouting and drinking beer in the streets and urinating openly” as early as 4pm.

Greg Clough said: “They were the most unwelcome guests. Trashing Highbury Fields, and deliberately vandalising cars and road signs with stickers.

Islington Gazette: FC Koln fans outside The Emirates. Picture: Nick Potts/PA WireFC Koln fans outside The Emirates. Picture: Nick Potts/PA Wire (Image: PA Wire)

“I made the mistake of walking my kids home from school through the fields. None of us felt safe!

“Arsenal need to stop selling tickets to away fans until they find a solution to the unruly crowds.”

Five people are being held on suspicion of public order offences.

Islington Gazette: FC Koln fans outside The White Swan. Picture: Nick Potts/PA WireFC Koln fans outside The White Swan. Picture: Nick Potts/PA Wire (Image: PA Wire)

Islington Gazette: Crowds block Highbury Corner this afternoon. Picture: TfL Bus Alerts/@TfLBusAlertsCrowds block Highbury Corner this afternoon. Picture: TfL Bus Alerts/@TfLBusAlerts (Image: Archant)