LIVERPOOL -- Everton have asked fans to help them investigate the trouble that flared up in Lille ahead of Thursday's Europa League tie.
The club are working with French police to examine two incidents in which travelling Toffees supporters suffered injuries.
A group of fans were attacked by around 50 hooligans outside a bar in the city centre on Wednesday night, which Everton described as "an unprovoked and planned attack by local youths."
In a separate incident in Lille's main square on Thursday afternoon, an Everton fan was taken to hospital with a gash above his eye after he was reportedly hit by a gas canister fired by police.
The French embassy said on Friday that police acted in self-defence when they used rubber bullets and a stun grenade after arresting a Toffees fan for selling drugs during the second incident.
The club have asked fans who witnessed either incident to give information via a feedback form on their website.
The club said: "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 ocurred in Lille ahead of our Europa League fixture this week."
A statement from the French embassy defended the use of police force in the main Grand Place square on Thursday.
The statement said: "At 2:20 p.m. on Oct. 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."
In their own statement regarding Thursday's trouble in the city square, Everton said: "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 to normal, with well-mannered and good-natured celebrations that were evident throughout the club's stay in Lille."
Meanwhile, Everton forward Kevin Mirallas is at least three weeks from making a comeback from his hamstring injury, according to manager Roberto Martinez.
The Belgium international has not played since being carried off on a stretcher during the Merseyside derby at Anfield on Sep. 27.
Martinez -- who did not comment on the trouble in Lille at a news conference on Friday -- is hopeful that Mirallas will return after the November international break, and could even be ready for the Premier League home match against West Ham on Nov. 22.
Ahead of Sunday's Premier League trip to Burnley, the manager said: "We're looking at Kevin being available after next month's international break.
"He's a sprinter, so we need to be careful. But the signs are positive.
"We hope that we will have a clearer idea after the international break."
Martinez also said that midfielder Ross Barkley is unique in European football.
The England midfielder, 20, has only just returned to action after two months out with medial knee ligament damage suffered just before their opening Premier League match at Leicester in August.
Martinez said: "Ross is a unique footballer. He's a player you are always going to miss when he is out.
"You can have like-for-like replacements with some players, but the way Ross plays is quite unique.
"We saw Ross come to life last season. It's very rare to see such ability in such a physically strong player.
"That's not just unique in English football. That's unique in European football."