Sniffer dogs followed their noses and helped find a stash of cigarettes during a raid in Worthing on Monday.
West Sussex County Council Trading Standards officers seized about 600 cigarettes in a shop and vehicle.
Acting on intelligence the officers moved in and found the cigarettes, helped by trained sniffer dogs YoYo and Scamp.
According to the council, the cigarettes are suspected to be counterfeit and will be sent for further testing as part of a criminal investigation.
The shop cannot be revealed while the investigation is ongoing.
Richard Sargeant, Trading Standards team manager, said: “Illegal, counterfeit tobacco can be extremely dangerous as it does not self-extinguish, which can then lead to house fires.
“We are very grateful to the residents who provided us with valuable information about this shop, and are committed to continue tackling this illegal trade.”
Readers with any information about illegal tobacco sales should let Trading Standards know by calling the Citizens Advice Consumer Helpline on 03454 04 05 06 or by reporting details online at www.westsussex.gov.uk/TSreport.