Defending champion Tadej Pogacar won a record-equalling third Tour of Flanders, but could face action after he was one of up to 20 riders who ran a red light at a railway crossing.
The East Flanders public prosecutor told BBC Sport it was investigating the incident which happened with more than 200km (124 miles) left in the race.
The peloton was told to stop at a level crossing as the lights turned to red, but a group at the front – including Pogacar and Remco Evenepoel – slipped across the tracks in pursuit of the early leaders.
Slovenian Pogacar said they had not been not given enough warning to slow down.
“Suddenly three guys jump on the middle of the road and start waving to stop,” he said.
“How can you stop in one second? I think they could prevent this by stopping us before, no? Not 10 metres before the crossing.
“I was thinking, maybe it’s like some protesters or something crazy is going on.”
According to Belgian media, the riders could reportedly face fines ranging from 320 euros (£280) to 4,000 euros (£3,500) and driving bans of eight days.
Pogacar, 27, has now won both Monument races this season, having triumphed at Milan-San Remo in March.
Sunday’s victory draws Pogacar level with Mathieu Van der Poel and six other cyclists on three wins at the Belgian event, having also won in 2023.
He now has 12 victories in Monuments – the five most prestigious one-day events in men’s road cycling – putting him clear in second in the all-time list behind only 19-time winner Eddy Merckx.
“It was a really crazy race today. I don’t know what to say – super-hard from I don’t know which kilometre,” Pogacar told Belgian television.
“I don’t race too much, so when I race there is pressure to win. So far everything went perfect for me, so I can be more than happy.
“Coming next week to Roubaix, I can go motivated, but I try to enjoy the cobbles.”
On his Flanders debut, double Olympic champion Evenepoel held off fellow Belgian Wout van Aert for third in the 278km race, which features punchy climbs and a number of cobbled sections.
