The teams’ Europa League clash was put back an hour after thousands of German fans arrived at the ground - after marching in central London during the day - with tickets for home areas and worried officials did not allow the stadium to be opened.
This led to major problems outside and stewards and police being attacked inside, although only five arrests were reported.
The match eventually went ahead with an estimated 8,000 Cologne fans dotted round the stadium, including 2,900 with legitimate tickets.
Both clubs were charged yesterday, Arsenal with one offence of allowing blocked stairways, which could see them fined £7,000, and the Germans with four - the crowd disturbances, setting off flares, throwing objects and acts of damage.
But they laid the blame firmly at Arsenal’s door in a hard-hitting statement.
It said: “Due to the enormous demand for tickets, it would have been sensible, not least for security reasons, to allow more than the allocated five per cent of stadium capacity to the guest fans.
“It was apparent that thousands of people from Cologne would seek to avoid the restrictions and get tickets in every way possible.
“One such way would be through the help of Arsenal supporters, who passed on their tickets to the FC fans.
“Some as gifts, but some also for horrendous prices. Arsenal FC has described the extent of this second ticket market as ‘disappointing’ and has announced that further clarifications of the circumstances will be evaluated.
“And also despite the tremendous experience of both the London security forces and Arsenal as a permanent partaker in European football, the organizers were unfortunately not adequately prepared for the task.
“In our view, the security concept and communication seemed inadequate and the police force too small.”
They made it clear they were not defending fans who threatened, insulted, and attacked stewards and police, and also apologised for events at the ground.
Arsenal said: “We have launched a full review into the circumstances surrounding the game.
“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.
“Many tickets were sold through touts and this is very disappointing and something we continue to work hard to address.”
Gunners skipper Per Mertesacker revealed how he feared for his family watching in the stands.
“I don’t know what happened outside, I just wanted to make sure my family was okay,” he said.
“Some people said ‘Tell them to stay at home’, because there were such big problems here outside of the stadium.
“It was very difficult to handle because we were already in the dressing-room and then we found out very late that we extended the decision about the kick-off for another hour.”
Arsenal return to Premier League action tomorrow at Chelsea, where they have lost in their last five Premier League games.
They have also lost their two away games this season, but boss Arsene Wenger insists they do not have a problem on their travels.
He said: “Last year, until we lost at Everton, we had not lost away from home for a whole year.
“Straight after that, we lost at Man City and it’s true that gave us a problem of confidence away from home.
“But I don’t really believe in that. The pitch is 105m long and 68m wide everywhere and never in my life I could accept or understand that it’s different away from home.
“It’s just a question of how much you want it, it’s about football.
“Sunday’s a good opportunity to show that and that we have that quality.”
