Kick-off was delayed for one hour after 17,000 fans of the German club arrived in north London without tickets. Arsenal went on to win the Group H clash 3-1.

Cologne had been allocated just 3,000 tickets for the game, with many more gathered outside the Emirates preventing home supporters from gaining entrance through turnstiles.

 

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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.

"The game has now concluded and the majority of supporters have left the stadium and the surrounding area."

But Wenger believes UEFA should take action, saying: "They are the only master to analyse the facts of what happened. They will certainly make an inquiry to see what happened, for sure."

Extra police were deployed at the Emirates Stadium following disorder before kick-off

And Ian Bolton, a senior reporter with Sky Sports News, provided his eyewitness account of the incident: "I was told the stadium was in lockdown as a police operation went on outside.

"Inside the stadium, it became apparent that Cologne fans were getting into an Arsenal section behind the goal at the south end of the stadium.

The giant screen shows that kick-off is delayed

"There were scuffles between away fans and stewards as Cologne fans tried to cross a line of stewards to try to get into the adjacent away section.

"Some succeeded in getting through. Others remained in the Arsenal section. Police wearing helmets, and with dogs arrived, and remained in position for the match.

Large numbers of Cologne fans were seen in London ahead of the game

"There were 3000 Cologne fans in the away section, in the south-east corner of the stadium, but thousands more had managed to get into the stadium.

"Probably several thousand in the section behind the goal adjacent to the 'away' area, and probably several thousand in the upper tier at the same end. There were also smaller groups of away fans in the middle tier.

"There was a line of stewards and police in the stand behind the goal at the southern 'clock' end, but there were Cologne fans either side of it!

"At the north end, there were many empty seats. Don't know if it was because Arsenal fans had decided not to come in the first place, or decided to go home once they got here."

Cologne said they needed to know more information before issuing a statement about the incident, with a club spokeswoman explaining: "We have to first inform ourselves and in the next few days we will talk about that."