Björg Lambrecht's fatal accident at the Tour de Pollogne was caused by reflectors built into the side of the road, according to an investigation by Polish prosecutors.The 22-year-old rider, Lot Soudal, died from his injuries after a crash on stage 3 of the race earlier this month.

"Two UAE Team Emirates riders who were right behind him saw him riding on reflectors built into the road surface," said prosecutor Malwina Senzieroz-Pawela, according to Polish media reports.

"As a result, he lost control of his bike and suddenly turned right and then left."

Lambrecht eventually crashed into a concrete pipe and sustained serious liver injuries.

According to the Belgian newspaper Het Laatste Nieuws, the reflector was 10x10 cm and 1.8 cm above the asphalt.

"It is sad that a resource that is supposed to improve road safety is the cause of such tragedies," Sengereutz-Pawela said.

Investigators have released preliminary findings and plan to interview the race doctor and race organizer Cheslav Lang.