Dozens of high-powered, illegal ebikes are in the hands of police after they were seized in a blitz across the Northern Beaches.

Operation E-Voltage included the seizure of an e-bike capable of going more than 90 kilometres an hour that was ridden by a 14-year-old boy.

Officers found one 14-year-old’s ebike was capable of hitting 90km/h. Owners have two weeks to appeal the seizure before the bikes will be crushed