The 24-year-old became the first Frenchman since 1995 to win the one-day classic, which features on the International Cycling Union (UCI) WorldTour, but was immediately met by claims he had cheated.

Demare had been caught up in a crash 30 kilometres from the finish of the race, but was able to rejoin the peloton after the ascent up the Cipressa climb.

After a chaotic finale to the race, which saw several of the favourites' challenge come to an end in crashes, Demare outsprinted Britain’s Ben Swift to earn the race win.

Italy’s Matteo Tosatto and Eros Capecchi, who ride for the Tinkoff and Astana teams respectively, both claim to have seen the Frenchman holding on to a team car in a bid to rejoin the lead group following his crash.

"Demare passed us climbing at 80 kilometres per hour, unheard of,” Capecchi told Italian newspaper Gazzetta dello Sport.

“I was at the wheel of Tosatto, I saw it all very well.

“Demare was clinging on the right of the team car, it’s disgusting.”

Race officials did not take any action against the FDJ rider, due to there being no video or photographic evidence of the offence having occurred.

Had there been evidence of such an offence, the race jury could have opted to disqualify the Frenchman from the race.

Demare has denied the accusations, although admitted drafting using the team cars, and believes his race data proves that the claim that he was travelling at 80kph is false.

"I have nothing to reproach myself, I have done nothing wrong,” he told the French newspaper L'Equipe. 

“There are referees in cycling, if I had done something forbidden, I would have been disqualified.

“It's part of cycling and has always been: we profit from the draft of the cars.

“They shelter us from the wind, it is not forbidden."

Italy's Vincenzo Nibali, a three-time Grand Tour winner, was disqualified from last year’s Vuelta a España  after television images showed he had been towed back to the peloton behind a team car after being caught behind a crash.