Driving instructors who have relationships with their young students risk being struck off the register.
Jacqui Turland, registrar for the Driver and Vehicle Standards Agency (DVSA), said she will treat sexual relationships between instructors and students under 18 as exploitation, even if consensual.
Breaching a position of trust in this way could mean instructors are considered a high risk to learners, and are removed from the approved driving instructor (ADI) register.
Head of counter-fraud and investigations at the DVSA, Andy Rice, said: "DVSA's priority is to help you through a lifetime of safe driving.
"We take the safety of learner drivers extremely seriously and will thoroughly investigate any complaints about the conduct of instructors, and will involve the police where necessary.
"Any driving instructors threatening the safety of learner drivers and failing to meet the 'fit and proper' criteria will be removed from the ADI register."
In 2016-17 there were 109 investigations into instructor misconduct, which includes inappropriate sexual behaviour.
All driving instructors are subject to enhanced criminal record checks which must be renewed every four years.