Besiktas supporters burn flares during the UEFA Europa League first leg quarter final football match against Lyon April 13, 2017, at the Parc Olympique Lyonnais stadium in Decines-Charpieu
Lyon and Besiktas are braced for punishment by UEFA over Thursday's violence-marred European tie as both clubs blamed opposing fans for instigating much of the trouble.
European football's governing body have opened an inquiry into the Europa League quarter-final first leg which was scarred by violence and a pitch invasion.
Lyon were hit with four charges, including "insufficient organisation" concerning the segregation of supporters, while Besiktas were charged with throwing projectiles and crowd disturbances.
UEFA could come down hard on Lyon as match organisers with sanctions ranging from a hefty fine to a supporter ban or playing their next European home tie at a neutral venue.
"As organisers of the game we are responsible," conceded Lyon's deputy chief legal director Vincent Ponsot on Friday.
"Except that in this instance it's clear we were victims of aggression from Turkish supporters," he told a press conference.
The start of the high-risk encounter in France had to be delayed 45 minutes as officials attempted to clear the pitch of scores of Lyon fans.
Hundreds of supporters had already run a gauntlet of violence outside the ground where police used teargas to quell outbreaks of fighting and vandalism.
Lyon supporters poured onto the pitch as they attempted to protect themselves from firecrackers and other objects raining down from the stands above.
"Twelve arrests from both sets of fans were made," a police spokesman said.
"Thrown objects slightly injured two fans who were taken to hospital," a local authority spokesperson added.
- Hardcore fans -
Five police officers were also slightly injured in the disturbances.
"Everything... is under the responsibility of Lyon. There is no need to punish Besiktas," club spokesman Metin Albayrak told state-run Anadolu news agency.
"The first priority of the home team is to provide a game played in secure and healthy conditions.
"If there is one who should be punished, it is Lyon, not Besiktas."
He added: "If a twentieth of the incidents were carried out in Turkey, Turkish clubs would be heavily punished."
Attention now turns to next week's second leg in Istanbul with Lyon president Jean-Michel Aulas expressing fear for the safety of his team and fans and raising the possibility of the tie being played behind closed doors.
Ponsot revealed that Lyon had "asked UEFA that the security of their players be guaranteed in Istanbul".
"Each club is responsible for its supporters but I am quite confident (that Lyon were not at fault)," said Ponsot.
"The video elements show it. We watched the events live with UEFA's security officer who could see where the incidents were coming from."
Lyon's own security officer Annie Saladin blamed a group of 50 hardcore Besiktas supporters for the trouble that led to scores of Lyon fans taking refuge on the pitch.
"They took control and given their profile we weren't able to contain them," she said.
Authorities had categorised the match as maximum risk with 1,000 stewards drafted in for the encounter held in an area of France's third city which is home to many people of Armenian origin.
Up to 20,000 Turkish fans, the majority living in France or Germany, were intermingled among the 35,000 supporters of Lyon on top of the 3,000 fans from Istanbul situated in the visitors' section.
"There's no such thing as zero risk," said Saladin. "And 500 or 1,000 extra stewards would not have changed anything."
The setting off of smoke bombs and firecrackers in the stadium raised further questions of stadium security.
But Saladin said: "Those who want to enter with a smoke or a firecracker will succeed. The stewards have done their frisking but they have to limit themselves to certain zones (on the body) and the supporters know that."
The match finally went ahead after Aulas appealed for calm over the tannoy, with Lyon winning 2-1.
Thursday's disturbing scenes from Lyon came on a black week for European club football after the Borussia Dortmund team bus was attacked with explosives on Tuesday just before their Champions League game at home to Monaco.
There was also trouble involving Leicester City fans when their team played a Champions League tie in Madrid in midweek.