Belgian rider Femke Van den Driessche has been suspended for six years by the UCI in the first case of motorised doping in cycling.
Disciplinary proceedings began in March after the 19-year-old allegedly used a bike containing a motor at January's UCI Cyclo-cross World Championships in Belgium.
The UCI announced on Tuesday that its disciplinary commission banned Van den Driessche for violating its rules relating to "technical fraud" while she has also been fined 20,000 Swiss Francs (?14,000) and been ordered to pay legal costs.
A Union Cycliste Internationale statement read: "Ms Femke Van den Driessche is found to have committed a violation of art. 1.3.010 in combination with art. 12.013bis (technological fraud) of the UCI Regulations.
"Ms Femke Van den Driessche is suspended for a period of six years starting from and including October 11, 2015 and ending on October 10, 2021."
In addition, Van den Driessche "is ordered to return the medals and the prize-monies she received in connection with the disqualified competitions to the respective organisers".
UCI president Brian Cookson said last month that the world governing body would request the toughest possible sanctions.
Regulations, recently strengthened, state that a rider is given a minimum suspension of six months and a fine of up to 200,000 Swiss Francs (?141,000) for an offence of "technological fraud", while coaches, mechanics and other officials could also be sanctioned.
Bikes have been scanned by the UCI at major competitions across all disciplines, including the Tour de France, in recent years following rumour and speculation regarding motors hidden in frames.
There were 274 bikes scanned at the Track Cycling World Championships in London in March.