The Former world champion Fabian Cancellara could be investigated over claims he used a hidden motor in his bike, says cycling's world governing body.
The Swiss rider was accused by former cyclist Phil Gaimon in his new book.
The allegations first surfaced after Cancellara's victories at the Tour of Flanders and Paris-Roubaix in 2010.
"We are not ruling out the possibility of investigating, especially if new information is made available," the UCI told BBC Sport.
Cancellara, who has been world time trial champion four times, has never been investigated and has always denied the allegations.
The two-time Olympic time-trial champion has won Paris-Roubaix three times and the Tour of Flanders three times.
He has also won the opening stage of the Tour de France five times and has led the race for 29 days total - the most of any rider who has not won the Tour.
"When you watch the footage, his accelerations don't look natural at all, like he's having trouble staying on the top of the pedals," American rider Gaimon wrote in his autobiography 'Draft Animals'.
Last year Belgian cyclo-cross rider Femke Van Den Driessche was banned for six year from cycling after being caught using a hidden motor at a world championship race.
She was the first cyclist banned by the ICU using its rules on technological fraud.
The motor was found using magnetic resonance scans of bikes in the pits area at the women's world under-23 cyclo-cross race in January 2016.