The Professional Cyclists' Association said it will take legal action and that a spectator was arrested after he threw potato chips at Tour de France leaders Tadej Pogacar and Visma-Jonas Vingegaard during Stage 14 on Saturday.
Charging solo up the last stretch of Pla d'Adet, Pogacar had to dodge a fan who leaped out to hurl a bag of chips at the Slovenian race leader.
The spectator did the same thing to Denmark's Vingegaard, who came through moments later.
"The [CPA] will take legal action against this guy with pleasure due to what he did to both [Pogacar] and [Vingegaard]," CPA president Adam Hansen wrote in a post on X on Saturday. "This is disrespectful and will not be tolerated."
Hansen posted on social media Sunday morning that the man had been arrested.
Vingegaard finished 39 seconds behind Pogacar while Belgium's Remco Evenepoel, who was second in the general classification before Stage 14, finished 70 seconds behind and slipped to third overall behind the Dane.
"There was quite a bit of booing, and someone was throwing chips. I heard also they threw the chips at Tadej, and that's strange to do," Vingegaard said after the stage. "Just stay off the road. I don't understand why you go to a bike race and boo at people."
Reuters contributed to this report.