Five teams, including Britain’s Ineos Grenadiers, pulled out of the third stage of the Etoile de Besseges road cycling race in France following incidents of traffic interfering with the peloton.
Friday’s stage from Besseges-Besseges was neutralised early on after riders came across a vehicle on a roundabout.
The day before, a motorist tried to enter the course as the riders were arriving at high speed on a narrow road 10 miles from the finish in Marguerittes, causing chaotic scenes in the peloton.
The incident forced 25-year-old Belgian rider Maxim Van Gils to abandon the race after he crashed and needed to go to hospital.
In a statement, Ineos said the safety of their riders and staff “is of paramount importance”.
Lidl-Trek, EF Education-EasyPost, Red Bull-Bora Hansgrohe and Soudal Quick-Step also withdrew from stage three because of safety concerns.
Soudal-QuickStep said it was “unacceptable” that unauthorised motor vehicles were allowed on the course.
It is not clear yet whether those teams will return for Saturday’s stage four from Vauvert to Mont Bouquet.
UCI Europe Tour posted on Instagram an image of riders trying to pass a lorry on the course, writing: “Pictures we don’t want to see.”
The post added: “The security of our riders is the most important thing. It’s not necessary to mention the names of the riders who died last year to prove that.”
Belgian rider Thomas de Gendt, who retired last year after 16 years as a professional, wrote on X: “Maybe now the organisers and UCI will start to listen. Otherwise we just stay monkeys in a circus.”
Governing body the UCI later issued a statement saying it was investigating and would act.
“Measures are being taken to avoid a repetition of the problems that occurred on these stages,” it said.
“The UCI emphasises that it takes the matter of rider security extremely seriously.”
Race organisers said they could not afford to fully close roads on the route but were doing what they could to protect riders.