The French Football League (LFP) has said Paris Saint-Germain will pay for the damage caused to Parc OL by their fans during Saturday's 4-1 Coupe de la Ligue final win over Monaco.
Seats at Lyon's stadium, the venue for the showpiece match, were ripped up, toilets were smashed and anti-Lyon graffiti was daubed on walls.
In a statement, the LFP said it "condemns the acts of vandalism committed yesterday evening by some PSG supporters at Parc OL after the Coupe de la Ligue final."
The statement added: "These events have tarnished the great sporting and popular success of this first de-localised final.
"In line with the regulations, Paris Saint-Germain must reimburse the cost of all of the very significant damage caused."
The LFP's Disciplinary Commission will open an investigation on Thursday.
Lyon president Jean-Michel Aulas said: "I cried about it last night.
"There was damage just for damage's sake. It wasn't out of disappointment, but out of a desire to break what belongs to our fans. It really, really hurts."
Suspicions over who caused the damage centred on the Collectif Ultra Paris (CUP) group of hardcore PSG fans.
#FinaleCDL, Communiqué de la @LFPfr ➡️ https://t.co/BmAfeQ74ri pic.twitter.com/5YgtLouTJv
- Parc OL (@ParcOL) April 2, 2017
L'Equipe reported the group did not present their banners and flags to the required security check, only arriving in Lyon late in the afternoon ahead of the evening kickoff.
Around 60 flares, which would normally have been confiscated during security searches, were used in the PSG section.
However, the CUP hit back in a statement to Le Parisien in which it condemned the damage caused.
"These acts of vandalism are unacceptable," it said. "They don't correspond to our philosophy, nor our association's rules of behaviour.
"We won't tolerate them. As a result, if we find that these actions are down to CUP members, we'll take our responsibilities and put into action the punishments laid down in our charter."
The group's vice-president, known only as Mika, claimed the CUP had respected all the instructions given.
"We had to do our own security -- it was a real mess," he said. "There were no searches, tickets weren't even checked, and our block was supposed to be secured by stewards.
"That wasn't the case, and there were a number of intruders."