Arsenal are being investigated in relation to crowd disturbances which occurred during Wednesday night's Champions League meeting with Galatasaray.
Flares were thrown onto the pitch from the away end of the Emirates Stadium as the Gunners defeated the Turkish club 4-1 courtesy of a Danny Welbeck hat-trick.
Metropolitan Police made six arrests on the night - two for having flares upon entry - and now UEFA will undertake a further investigation into the incidents.
It is believed that the home teams at European matches are required to stop any such happenings by halting potential offenders at the gate meaning Arsenal, who had the responsibility, and Galatasaray, who allegedly committed the misdemeanors, could face sanctions.
An Arsenal spokesman said in a statement: "Crowd safety is always a top priority for us and we were disappointed with the incidents last night, which occurred despite extensive searches of away supporters as they entered the stadium and close liaison with police, UEFA and visiting club officials."
