More than 25,000 illegal cigarettes have been seized in raids on shops across Oxfordshire.
Trading Standards and police officers discovered the cigarettes - with an estimated street value of £8,000 - at shops in Witney and Cowley.
The raids are part of a crackdown to reduce smoking rates.
Jody Kerman from Oxfordshire Trading Standards said illegal tobacco is "sold at pocket money prices which kids can afford".
The teams raided three shops following undercover surveillance and tip-offs from the public.
Trading Standards say illegal cigarettes have a negative impact on legitimate businesses, and they reduce tax revenue leaving less money for the NHS to help people with smoking related diseases.
"The main point of our work is around health improvement. It's about taking out the supply of cheap tobacco so that those who really want to quit smoking are helped to give up," Mr Kerman said.
"We're worried about the next generation of smokers. These cigarettes are sold by people who are already breaking the law so they're not going to care who they sell to.
"We don't want young people coming into contact with criminals."
Trading Standards said it has seen a rise in the number of tip-offs from the public since Oxfordshire County Council invested in a dedicated tobacco control officer last year.
The work is part of a year-long crackdown which began in October.
Since then 32,000 illegal cigarettes have been seized in Oxfordshire.