Marseille have expressed their "outrage" after midfielder Florian Thauvin was the target of an attack when the team landed in Lille on Monday night.
OM landed to a hostile reception, with footage on L'Equipe's website showing a scuffle breaking out as members of the club entered a crowded main hall of Lille's Lesquin Airport.
OM released a statement on Tuesday morning claiming Thauvin - who left Lille in acrimonious circumstances in the summer - had to be protected by club staff and plain-clothed policemen after he was targeted by 20 people they believed to be LOSC fans.
"Olympique Marseille deplores the reception on Monday night at the airport Lesquin," the statement read.
"Around 20 people thought to be supporters of LOSC insulted and tried to shake Florian Thauvin as he got off the aircraft.
"The young player of OM had to be protected by the stewards of the club and by the intervention of plain-clothed policemen present in the hall landing.
"Olympique Marseille wishes to express its outrage to such acts."
Lille went on to win the match 1-0 courtesy of a stoppage-time goal from Nolan Roux.
Thauvin, 20, earned the ire of the club and its fans in the summer after he refused to train as he tried to force a move through to Marseille.
The France Under-21s international only moved to LOSC for 3.5million euros in January, but did not make an appearance after being sent back to Bastia on loan.
Lille chairman Michel Seydoux was publicly critical of Thauvin's attitude at the time but - after selling him to OM for 15 million euros - revealed he had moved on from the incident.
"The page has been turned," he told RMC.
"There was a lively and original story, but now it's over. Everyone's in his place. I think (Marseille manager) Elie Baup is happy, we're not unhappy. And we're content that Florian is working well at Marseille."
