Watch: UEFA set to act after crowd trouble forces delay between Arsenal and Cologne

Thousands of ticketless Cologne supporters turned up at the Emirates Stadium and those fans with tickets were unable to gain access to the ground. The 60-minute delay was announced inside the stadium with Arsenal "monitoring" the situation.

Hundreds of Cologne supporters were being held behind a police cordon as order was being restored in and around the away turnstiles.

Inside the ground a number of away fans attempted to enter the home sections of the stadium with legitimate tickets.

Earlier yesterday, Cologne supporters flooded into central London as around 20,000 fans of the Bundesliga side were expected in the capital despite only 3,000 tickets being available.

Hordes Fans took to the streets in their numbers, with social media posts showing hordes of supporters singing and marching around Oxford Circus hours before the scheduled 8.05pm kick-off.

Liverpool have written to UEFA seeking clarification on whether disciplinary proceedings against Spartak Moscow will have any impact on their forthcoming Champions League match in Russia. Europe's governing body have charged Spartak on foot of unruly scenes in their opening group fixture against Slovenian side Maribor, during which fans set off fireworks and threw missiles.

Uefa will determine what action to take on September 21 - just five days before Liverpool play in the Russian capital. One of the possible sanctions is for the fixture to be played behind closed doors, which would have an impact on travelling fans.

Meanwhile, Burnley goalkeeper Tom Heaton is facing a least a month on the sidelines after undergoing surgery on the shoulder injury he suffered during the first half of the Clarets' 1-0 win over Crystal Palace last Sunday.