The spectator who threw a water bottle at Mathieu van der Poel during last weekend’s Paris-Roubaix has issued a public apology, calling his act a "stupid gesture."

The Lille public prosecutor's office confirmed Monday that it has launched an investigation into "violence with a weapon." The 28-year-old man turned himself in to Belgian police after the race.

Dutch rider Van der Poel went on to win the race for the third consecutive year despite the incident.

Drunken Decision Leads To Dangerous Incident

"I'm so happy that he crossed the finish line first on Sunday, despite my stupid gesture," the man said in a letter published by Belgian daily *Het Laatste Nieuws* on Wednesday.

"At the same time, I realize that I must apologize to all the riders and all the racing fans. A water bottle was on the grass. I picked it up and threw it as he passed by—without thinking. After half a second, I realized how stupid and dangerous it was. I was very embarrassed for days."

The fan admitted he had "drunk a lot" at the time of the incident, which took place on one of the cobbled sectors of the Paris-Roubaix course.

Mathieu Van Der Poel Condemns Escalating Abuse

Van der Poel’s team, Alpecin-Deceuninck, called the act “dangerous and unacceptable.” The Dutch rider himself compared the impact of the full bottle to being “hit in the face with a stone.”

"It was a full bidon. It weighed half a kilo and I was riding at 40 kph," Van der Poel said. "It is unacceptable."

Van der Poel, a seven-time cyclo-cross world champion, has previously been the target of abuse during races, including multiple spitting incidents.

Local police in Ronse confirmed Tuesday that a spectator who spat at Van der Poel during the E3 Classic last month has been identified and will be fined.