Television station France 2, in collaboration with Italian newspaper Corriere della Sera, claimed that hidden motors were used in the Strade Bianche one-day race and the Coppi e Bartali race in Italy this season.
The report used thermal imaging to argue that five motors were hidden in the seat tube and two in the rear hub, but added they could not prove it beyond all reasonable doubt.
The UCI did not respond specifically on the accusation but said they were happy with their methods, which have found one hidden motor earlier this year in the bike of Belgian Femke Van den Driessche at the Under-23 cyclocross world championships.
"We have been trialling new methods of detection over the last year," the UCI told Reuters in an email statement.
"We have looked at thermal imaging, X-ray and ultrasonic testing but by far the most cost effective, reliable and accurate method has proved to be magnetic resonance testing using software we have created in partnership with a company of specialist developers.
"The scanning is done with a tablet and enables an operator to test the frame and wheels of a bike in less than a minute."
The UCI added it had tested 216 bikes at the Tour of Flanders and 224 at Paris-Roubaix earlier this month.
"We are confident that we now have a method of detection that is extremely efficient and easy to deploy," the governing body said.