Around 5,500 Everton fans made the trip to northern France for the Europa League Group H match, which ended in a 0-0 draw, and there were two incidents in the city centre in the 24 hours leading up to kick-off.
A group of supporters were reportedly set upon at a bar on Wednesday night and a flare up in the main square on Thursday lunchtime saw the local police use tear gas to break up clashes between rival fans.
A statement from the Premier League club read: “Everton will continue to work closely with the French and Merseyside police, in conjunction with the club’s own security team, to better understand the two isolated but serious incidents that occurred in Lille ahead of our Europa League fixture this week.
“All available reports suggest that the first incident, on the night before??the game, was an unprovoked and planned attack by local youths.
“The second incident, early in the afternoon on matchday, in the city’s main??square, quickly escalated into unwelcome and unpleasant scenes.
“Events then, equally quickly, returned back to normal with well-mannered and??good-natured celebrations that were evident throughout the club’s stay in??Lille.
“The club will now work with all authorities to find out what happened and??why.
“In order to gather as much detail as possible on the incidents and on other??issues encountered by fans, the club has provided an online feedback form.”
A statement from the French embassy also confirmed rubber bullets were fired on two occasions and a stun grenade was deployed after Everton fans threw missiles.
Their statement read: “At 2.20 pm on October 23, 2014, police responsible for security in the main square, where about 1,000 British fans had gathered ahead of the Europa League match between Lille and Everton, noticed that one of them – already spotted in Wednesday’s brawl – was selling drugs.
“The individual was arrested, but the action sparked a hostile reaction??against the police, who had missiles thrown at them.
“Intervention teams drove back the rioters, using a stun grenade and firing??twice with rubber bullets in self-defence.
“No members of the security forces were hurt, and no further arrests were??made.
“The individual arrested over the drugs was remanded in custody at the local??police station, which has been tasked with the investigation.”